diff --git a/org.ntlab.reverseDebugger/src/org/ntlab/reverseDebugger/ObjectFlowAliasView.java b/org.ntlab.reverseDebugger/src/org/ntlab/reverseDebugger/ObjectFlowAliasView.java
index f8c7a19..abbb9ff 100644
--- a/org.ntlab.reverseDebugger/src/org/ntlab/reverseDebugger/ObjectFlowAliasView.java
+++ b/org.ntlab.reverseDebugger/src/org/ntlab/reverseDebugger/ObjectFlowAliasView.java
@@ -82,8 +82,12 @@
 				IStructuredSelection sel = (IStructuredSelection)event.getSelection();
 				Object element = sel.getFirstElement();
 				if (element instanceof JDIInstanceMethodCaller) {
-					selectObjectFlowAlias = (JDIInstanceMethodCaller)element;
-					javaEditorOperator.openSrcFileOfAlias(selectObjectFlowAlias);
+					if (((JDIInstanceMethodCaller)element).getReceiver() != null) {
+						selectObjectFlowAlias = (JDIInstanceMethodCaller)element;
+						javaEditorOperator.openSrcFileOfAlias(selectObjectFlowAlias);
+					} else {
+						selectObjectFlowAlias = null;
+					}
 				}
 			}
 		});	
@@ -152,11 +156,13 @@
 	}
 	
 	private void findSeedAliases() {
-		SeedAliasView.createSeedAliasesByAlias(selectObjectFlowAlias);
-		SeedAliasView.refresh();
-		CallStackView.updateByAlias(selectObjectFlowAlias);
-		CallStackView.refresh();
-		javaEditorOperator.openSrcFileOfAlias(selectObjectFlowAlias);
+		if (selectObjectFlowAlias != null) {
+			SeedAliasView.createSeedAliasesByAlias(selectObjectFlowAlias);
+			SeedAliasView.refresh();
+			CallStackView.updateByAlias(selectObjectFlowAlias);
+			CallStackView.refresh();
+			javaEditorOperator.openSrcFileOfAlias(selectObjectFlowAlias);
+		}
 	}
 	
 	public static void refresh() {