diff --git a/R/ds.Boole.R b/R/ds.Boole.R
index 31f14074..b3171efd 100644
--- a/R/ds.Boole.R
+++ b/R/ds.Boole.R
@@ -149,7 +149,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asCharacter.R b/R/ds.asCharacter.R
index 9df62c8e..aa8ce5fc 100644
--- a/R/ds.asCharacter.R
+++ b/R/ds.asCharacter.R
@@ -78,7 +78,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asDataMatrix.R b/R/ds.asDataMatrix.R
index 87708c7a..e704f0e0 100644
--- a/R/ds.asDataMatrix.R
+++ b/R/ds.asDataMatrix.R
@@ -85,7 +85,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asFactor.R b/R/ds.asFactor.R
index 6e2cec7c..b89f7542 100644
--- a/R/ds.asFactor.R
+++ b/R/ds.asFactor.R
@@ -193,7 +193,7 @@ for(j in 1:num.datasources){																			 #
 	if(!object.info[[j]]$test.obj.exists){																 #
 		obj.name.exists.in.all.sources<-FALSE															 #
 		}																								 #
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 #
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 #
 		obj.non.null.in.all.sources<-FALSE																 #
 		}																								 #
 	}																									 #
diff --git a/R/ds.asInteger.R b/R/ds.asInteger.R
index c9989c95..d326a613 100644
--- a/R/ds.asInteger.R
+++ b/R/ds.asInteger.R
@@ -78,7 +78,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asLogical.R b/R/ds.asLogical.R
index 3728033b..e0ed38eb 100644
--- a/R/ds.asLogical.R
+++ b/R/ds.asLogical.R
@@ -78,7 +78,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asMatrix.R b/R/ds.asMatrix.R
index b9a14089..9b01d5f7 100644
--- a/R/ds.asMatrix.R
+++ b/R/ds.asMatrix.R
@@ -84,7 +84,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.asNumeric.R b/R/ds.asNumeric.R
index 95c80946..75caa012 100644
--- a/R/ds.asNumeric.R
+++ b/R/ds.asNumeric.R
@@ -78,7 +78,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.cbind.R b/R/ds.cbind.R
index 9e7880cf..8a1f7987 100644
--- a/R/ds.cbind.R
+++ b/R/ds.cbind.R
@@ -236,7 +236,7 @@ for(j in 1:num.datasources){										    #
 	if(!object.info[[j]]$test.obj.exists){								    #
 		obj.name.exists.in.all.sources<-FALSE							    #
 		}											    #
-	if(object.info[[j]]$test.obj.class=="ABSENT"){						            #
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){						            #
 		obj.non.null.in.all.sources<-FALSE						            #
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.dataFrame.R b/R/ds.dataFrame.R
index 59b61d72..88004f25 100644
--- a/R/ds.dataFrame.R
+++ b/R/ds.dataFrame.R
@@ -232,7 +232,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.dataFrameFill.R b/R/ds.dataFrameFill.R
index cd6fb501..5e0d86b8 100644
--- a/R/ds.dataFrameFill.R
+++ b/R/ds.dataFrameFill.R
@@ -102,7 +102,7 @@ ds.dataFrameFill <- function(df.name=NULL, newobj=NULL, datasources=NULL){
     if(!object.info[[j]]$test.obj.exists){
       obj.name.exists.in.all.sources <- FALSE
     }
-    if(object.info[[j]]$test.obj.class=="ABSENT"){
+    if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){
       obj.non.null.in.all.sources <- FALSE
     }
   }
diff --git a/R/ds.dataFrameSort.R b/R/ds.dataFrameSort.R
index b536df90..c3a92376 100644
--- a/R/ds.dataFrameSort.R
+++ b/R/ds.dataFrameSort.R
@@ -122,7 +122,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.dataFrameSubset.R b/R/ds.dataFrameSubset.R
index c72a03ed..ac3c9549 100644
--- a/R/ds.dataFrameSubset.R
+++ b/R/ds.dataFrameSubset.R
@@ -203,7 +203,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.make.R b/R/ds.make.R
index 2f1b2cf2..5d6b3345 100644
--- a/R/ds.make.R
+++ b/R/ds.make.R
@@ -133,7 +133,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrix.R b/R/ds.matrix.R
index 938e7896..24ded4d7 100644
--- a/R/ds.matrix.R
+++ b/R/ds.matrix.R
@@ -240,7 +240,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixDet.R b/R/ds.matrixDet.R
index d699933d..38200c26 100644
--- a/R/ds.matrixDet.R
+++ b/R/ds.matrixDet.R
@@ -112,7 +112,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixDiag.R b/R/ds.matrixDiag.R
index 098f0afb..5f3f38f4 100644
--- a/R/ds.matrixDiag.R
+++ b/R/ds.matrixDiag.R
@@ -166,7 +166,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixDimnames.R b/R/ds.matrixDimnames.R
index 5edbf3ad..41a214ea 100644
--- a/R/ds.matrixDimnames.R
+++ b/R/ds.matrixDimnames.R
@@ -98,7 +98,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixInvert.R b/R/ds.matrixInvert.R
index 9cb7d87a..0a88bce0 100644
--- a/R/ds.matrixInvert.R
+++ b/R/ds.matrixInvert.R
@@ -81,7 +81,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixMult.R b/R/ds.matrixMult.R
index a018cf31..25472286 100644
--- a/R/ds.matrixMult.R
+++ b/R/ds.matrixMult.R
@@ -94,7 +94,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.matrixTranspose.R b/R/ds.matrixTranspose.R
index 9936792c..14ce8ec2 100644
--- a/R/ds.matrixTranspose.R
+++ b/R/ds.matrixTranspose.R
@@ -82,7 +82,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.merge.R b/R/ds.merge.R
index 0af69d3a..1ec94397 100644
--- a/R/ds.merge.R
+++ b/R/ds.merge.R
@@ -153,7 +153,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.rBinom.R b/R/ds.rBinom.R
index 17e72df9..92304bfb 100644
--- a/R/ds.rBinom.R
+++ b/R/ds.rBinom.R
@@ -255,7 +255,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.rNorm.R b/R/ds.rNorm.R
index 1f3a6000..68248d9b 100644
--- a/R/ds.rNorm.R
+++ b/R/ds.rNorm.R
@@ -244,7 +244,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.rPois.R b/R/ds.rPois.R
index 015bf045..628466db 100644
--- a/R/ds.rPois.R
+++ b/R/ds.rPois.R
@@ -220,7 +220,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.rUnif.R b/R/ds.rUnif.R
index 3f2dd240..9f65eccd 100644
--- a/R/ds.rUnif.R
+++ b/R/ds.rUnif.R
@@ -255,7 +255,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.rbind.R b/R/ds.rbind.R
index 11529110..16b9c8cc 100644
--- a/R/ds.rbind.R
+++ b/R/ds.rbind.R
@@ -233,7 +233,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.reShape.R b/R/ds.reShape.R
index f6900983..540547e8 100644
--- a/R/ds.reShape.R
+++ b/R/ds.reShape.R
@@ -135,7 +135,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.recodeValues.R b/R/ds.recodeValues.R
index 0ea18d05..851664dc 100644
--- a/R/ds.recodeValues.R
+++ b/R/ds.recodeValues.R
@@ -190,7 +190,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.seq.R b/R/ds.seq.R
index 1f7cf81e..06064581 100644
--- a/R/ds.seq.R
+++ b/R/ds.seq.R
@@ -147,7 +147,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.tapply.assign.R b/R/ds.tapply.assign.R
index 74d82176..bfe19252 100644
--- a/R/ds.tapply.assign.R
+++ b/R/ds.tapply.assign.R
@@ -132,7 +132,7 @@ for(j in 1:num.datasources){																			 	#
 	if(!object.info[[j]]$test.obj.exists){																 	#
 		obj.name.exists.in.all.sources<-FALSE															 	#
 		}																								 	#
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 	#
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 	#
 		obj.non.null.in.all.sources<-FALSE																 	#
 		}																								 	#
 	}																									 	#
diff --git a/R/ds.testObjExists.R b/R/ds.testObjExists.R
index 0c54aa1a..679a7fe5 100644
--- a/R/ds.testObjExists.R
+++ b/R/ds.testObjExists.R
@@ -61,7 +61,7 @@ for(j in 1:num.datasources){																			 #
 	if(!object.info[[j]]$test.obj.exists){																 #
 		obj.name.exists.in.all.sources<-FALSE															 #
 		}																								 #
-	if(object.info[[j]]$test.obj.class=="ABSENT"){														 #
+	if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){														 #
 		obj.non.null.in.all.sources<-FALSE																 #
 		}																								 #
 	}																									 #
@@ -102,7 +102,7 @@ if(obj.name.exists.in.all.sources && obj.non.null.in.all.sources){										 #
     if(!object.info[[j]]$test.obj.exists){
       obj.name.exists.in.all.sources <- FALSE
     }
-    if(object.info[[j]]$test.obj.class=="ABSENT"){
+    if(is.null(object.info[[j]]$test.obj.class) || object.info[[j]]$test.obj.class=="ABSENT"){
       obj.non.null.in.all.sources <- FALSE
     }
   }