diff --git a/org.ntlab.traceAnalyzer/src/org/ntlab/trace/ThreadInstance.java b/org.ntlab.traceAnalyzer/src/org/ntlab/trace/ThreadInstance.java
index 272a062..a88d9c4 100644
--- a/org.ntlab.traceAnalyzer/src/org/ntlab/trace/ThreadInstance.java
+++ b/org.ntlab.traceAnalyzer/src/org/ntlab/trace/ThreadInstance.java
@@ -29,7 +29,9 @@
 	}
 
 	public void preCallMethod(String callerSideSignature, int lineNumOfInvocationStatement) {
-		curMethodInvocation = new MethodInvocation(callerSideSignature, curMethodExecution.getThisClassName(), curMethodExecution.getThisObjId(), lineNumOfInvocationStatement, id);
+		if (curMethodExecution != null) {
+			curMethodInvocation = new MethodInvocation(callerSideSignature, curMethodExecution.getThisClassName(), curMethodExecution.getThisObjId(), lineNumOfInvocationStatement, id);
+		}
 	}
 	
 	public void callMethod(String signature, String callerSideSignature, String receiverClassName, String receiverObjId,