Error in IDoc to SOAP using Web service security - HTTP 200 OK

Hi,

We have an IDoc to SOAP scenario.

We have enabled the Web service security in SOAP receiver.

When we send a message the RWB log is as follows:

Success SOAP: apply Web Services Security... 
Success SOAP: Web Services Security applied. 
Error SOAP: call failed: java.io.IOException: java.lang.NullPointerException; HTTP 200 OK

In SOAP receiver , I have unchecked the Do not use Soap Envelope.

If I tick it, the Message is processsed successfully. But, the Web service security is not applied.

Please suggest...