diff --git a/AlgebraicDataflowArchitectureModel/src/application/editor/InputEventCellEditor.java b/AlgebraicDataflowArchitectureModel/src/application/editor/InputEventCellEditor.java
index 91f1dae..ee5eee9 100644
--- a/AlgebraicDataflowArchitectureModel/src/application/editor/InputEventCellEditor.java
+++ b/AlgebraicDataflowArchitectureModel/src/application/editor/InputEventCellEditor.java
@@ -131,37 +131,41 @@
 				}
 			}
 			    
-			String[] eventList = messages.toArray(new String[messages.size()]);
-			JComboBox<String> event = new JComboBox<String>(eventList);
-			
-			JPanel eventChoice = new JPanel();
-			eventChoice.add(event);//FirstEventChoice
-			
-			int ret = JOptionPane.showConfirmDialog(null, eventChoice, "Event Choice", JOptionPane.OK_CANCEL_OPTION);
-			if (ret == JOptionPane.OK_OPTION) {
+			if (messages.isEmpty()) {
+				return;
+			} else {
+				String[] eventList = messages.toArray(new String[messages.size()]);
+				JComboBox<String> event = new JComboBox<String>(eventList);
 				
-				JPanel inputEvent = new JPanel();
-				JTextArea textArea = new JTextArea(eventMessages.get(0).toString(), 10, 30);//EventInput
-				inputEvent.add(textArea);
-			
-				int approve = JOptionPane.showConfirmDialog(null, inputEvent, "Event Code", JOptionPane.OK_CANCEL_OPTION);
-				if (approve == JOptionPane.OK_OPTION) {
-					try {
+				JPanel eventChoice = new JPanel();
+				eventChoice.add(event);//FirstEventChoice
+				
+				int ret = JOptionPane.showConfirmDialog(null, eventChoice, "Event Choice", JOptionPane.OK_CANCEL_OPTION);
+				if (ret == JOptionPane.OK_OPTION) {
 					
-					TokenStream stream = new Parser.TokenStream();
-					Parser parser = new Parser(stream);
-					stream.addLine(textArea.getText());
-					Expression eventMessage = parser.parseTerm(stream,simulator.getModel());
-					
-					Event newEvent = new Event(eventChs.get(0), eventMessage, eventResPath, simulator.getCurState().getResource(resId)); 
-					simulator.transition(newEvent);
-					
-					constructNextSimulateGraph(simulator.getCurState().getRootResources(), simulator.getModel(),simulator.getModel().getDataFlowGraph(), graph);
-					graphComponent.setCellEditor(new InputEventCellEditor(graphComponent, simulator, this.editor, graph));
-					
-					} catch (ParameterizedIdentifierIsFutureWork | ResolvingMultipleDefinitionIsFutureWork
-							| InvalidMessage | UnificationFailed | ValueUndefined | ExpectedRightBracket | WrongJsonExpression | ExpectedColon e) {
-						e.printStackTrace();
+					JPanel inputEvent = new JPanel();
+					JTextArea textArea = new JTextArea(eventMessages.get(0).toString(), 10, 30);//EventInput
+					inputEvent.add(textArea);
+				
+					int approve = JOptionPane.showConfirmDialog(null, inputEvent, "Event Code", JOptionPane.OK_CANCEL_OPTION);
+					if (approve == JOptionPane.OK_OPTION) {
+						try {
+						
+						TokenStream stream = new Parser.TokenStream();
+						Parser parser = new Parser(stream);
+						stream.addLine(textArea.getText());
+						Expression eventMessage = parser.parseTerm(stream,simulator.getModel());
+						
+						Event newEvent = new Event(eventChs.get(0), eventMessage, eventResPath, simulator.getCurState().getResource(resId)); 
+						simulator.transition(newEvent);
+						
+						constructNextSimulateGraph(simulator.getCurState().getRootResources(), simulator.getModel(),simulator.getModel().getDataFlowGraph(), graph);
+						graphComponent.setCellEditor(new InputEventCellEditor(graphComponent, simulator, this.editor, graph));
+						
+						} catch (ParameterizedIdentifierIsFutureWork | ResolvingMultipleDefinitionIsFutureWork
+								| InvalidMessage | UnificationFailed | ValueUndefined | ExpectedRightBracket | WrongJsonExpression | ExpectedColon e) {
+							e.printStackTrace();
+						}
 					}
 				}
 			}