diff --git a/src/org/ntlab/deltaViewer/CollaborationViewer.java b/src/org/ntlab/deltaViewer/CollaborationViewer.java
index 1db4730..19f68a0 100644
--- a/src/org/ntlab/deltaViewer/CollaborationViewer.java
+++ b/src/org/ntlab/deltaViewer/CollaborationViewer.java
@@ -185,7 +185,16 @@
 				tgtObjId = calledMethodExec.getArguments().get(0).getId();
 				ObjectVertex tgtObjectVertex = objectToVertexMap.get(tgtObjId);
 
-				createObjectRefrence(srcClassName, srcObjId, tgtObjId);
+				if (!methodExecToVertexMap.containsKey(calledMethodExec)) {
+					createMethodExecutionVertex(calledMethodExec.getThisObjId(), methodInvStatement.getCallerSideMethodName(), calledMethodExec);
+					update();
+					moveArgumentObjectVertex(calledMethodExec, tgtObjectVertex, methodExecToVertexMap.get(calledMethodExec));
+					update();
+					createObjectRefrence(srcClassName, srcObjId, tgtObjId);
+					removeCalledMethodExecutionVertex(null, prevMethodExec, calledMethodExec);
+				} else {
+					createObjectRefrence(srcClassName, srcObjId, tgtObjId);
+				}
 				if (methodExecToVertexMap.containsKey(prevMethodExec)) {
 					if (methodExecToVertexMap.get(prevMethodExec).getLocals().contains(tgtObjectVertex)) {
 						methodExecToVertexMap.get(prevMethodExec).getLocals().remove(tgtObjectVertex);