diff --git a/src/org/ntlab/deltaViewer/CollaborationViewer.java b/src/org/ntlab/deltaViewer/CollaborationViewer.java
index 70a332e..9b9ef31 100644
--- a/src/org/ntlab/deltaViewer/CollaborationViewer.java
+++ b/src/org/ntlab/deltaViewer/CollaborationViewer.java
@@ -431,7 +431,7 @@
 				createMethodExecutionVertex(callerMethodExec.getThisObjId(), callerMethodExec.getSignature(), callerMethodExec);
 			}
 			createMethodExecutionVertex(objId, methodExecSignature, methodExec);
-		} else if (alias.getObjectId().matches("0") && !methodExecToVertexMap.containsKey(methodExec)) {
+		} else if (alias.getObjectId().startsWith("0:") && !methodExecToVertexMap.containsKey(methodExec)) {
 			createMethodExecutionVertex(objId, methodExecSignature, methodExec);
 		}		
 	}