diff --git a/src/org/ntlab/deltaViewer/DeltaViewer.java b/src/org/ntlab/deltaViewer/DeltaViewer.java
index 0d8b82a..4f52ab5 100644
--- a/src/org/ntlab/deltaViewer/DeltaViewer.java
+++ b/src/org/ntlab/deltaViewer/DeltaViewer.java
@@ -494,7 +494,13 @@
 							System.out.println(methodExecToVertexMap.get(methodExec).getLabel() + " :removeArgument: " + tgtObjectVertex.getLabel());
 						}
 					}
-					removeCalledMethodExecutionVertex(objectToVertexMap.get(srcObjId), methodExec.getCallerMethodExecution(), methodExec);
+					List<MethodExecution> methodExecList = new ArrayList<>(methodExecToVertexMap.keySet());
+					System.out.println(methodExecList.size());
+					if (methodExecList.size() > 1) {
+						removeCalledMethodExecutionVertex(null, methodExec.getCallerMethodExecution(), methodExec);
+					} else {
+						removeCalledMethodExecutionVertex(null, null, methodExec);						
+					}
 					updateObjectVertices();
 				} else {
 					// this to another
@@ -669,7 +675,13 @@
 						objectToVertexMap.put(ref.getDstObjectId(), new ObjectVertex(ref.getDstClassName(), vertex, xCor + (time * (srcSideSize - i)), yCor + (time * (srcSideSize - i))));
 					}
 				} else {
-					objectToVertexMap.put(ref.getSrcObjectId(), new ObjectVertex(ref.getSrcClassName(), null, xCor + (time * ((srcSideSize - 1) - i)), yCor + (time * ((srcSideSize - 1) - i))));
+					String srcClassName = ref.getSrcClassName();
+					if (srcClassName.contains("[L")) {
+						srcClassName = formatArrayName(srcClassName);
+					}
+					Object vertex = mxgraph.insertDeltaVertex(mxDefaultParent, ref.getSrcObjectId(), srcClassName, xCor + (time * ((srcSideSize - 1) - i)), yCor + (time * ((srcSideSize - 1) - i)), VERTEX_OBJECT_SIZE.getWidth(), VERTEX_OBJECT_SIZE.getHeight(), "fillColor=white"); //creates a white vertex. 
+					objectToVertexMap.put(ref.getSrcObjectId(), new ObjectVertex(ref.getSrcClassName(), vertex, xCor + (time * ((srcSideSize - 1) - i)), yCor + (time * ((srcSideSize - 1) - i))));
+					objectToVertexMap.put(ref.getDstObjectId(), new ObjectVertex(ref.getDstClassName(), null, xCor + (time * (srcSideSize - i)), yCor + (time * (srcSideSize - i))));
 				}
 			}
 
@@ -1447,9 +1459,13 @@
 
 		//  Remove sourceVertex from Locals and Arguments Vertex of CalledMethodExecution's Vertex.  
 		if (methodExecToVertexMap.containsKey(calledMethodExec)) {
-			mxICell sourceVertexCell = (mxICell)methodExecToVertexMap.get(methodExec).getCell();
-			mxCell targetVertexCell = (mxCell)methodExecToVertexMap.get(calledMethodExec).getCell();
-
+			mxICell sourceVertexCell = null;
+			mxCell targetVertexCell = null;
+			
+			if (methodExec != null) {
+			sourceVertexCell = (mxICell)methodExecToVertexMap.get(methodExec).getCell();
+			targetVertexCell = (mxCell)methodExecToVertexMap.get(calledMethodExec).getCell();
+			}
 //			if(!calledMethodExec.isStatic()) {
 			// Add a vertex to the graph in a transactional fashion. The vertex is actually a 'cell' in jgraphx terminology.
 			mxgraph.getModel().beginUpdate();
@@ -1503,7 +1519,9 @@
 						}
 					}
 				}
-
+				
+				if (sourceVertexCell == null || targetVertexCell == null) return;
+				
 				mxgraph.removeCells(mxgraph.getEdgesBetween(sourceVertexCell, targetVertexCell));
 				try {
 					mxICell cloneTargetVertexCell = (mxICell) mxgraph.addCell(targetVertexCell.clone());