Getting NullPointerException from WSSecurityUtil.findElement method

[Sarkar, Abanindra]

Hi,
 
  I was try to sign the following SOAP Message using WSS4J 1.5.1
library, but the WSSecurityUtil.findElement is throwing a
NullPointerException while try to retrieve the Body element from the
Envelope. Following is the SOAP message I am sending
 
<?xml version=\"1.0\" encoding=\"UTF-8\"?> 
    <soapenv:Envelope 
           xmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope/\
            xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\
            xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\";>
         <soapenv:Body> 
                <mesa:mesaAuth
xmlns:mesa=\"http://www.sterlingcommerce.com/mesa\";> 
                   <principal>admin</principal> 
                   <auth hashType=\"NONE\">password</auth> 
                </mesa:mesaAuth> 
                <mesa:LightweightJDBCAdapterQuery 
 
xmlns:mesa=\"http://www.sterlingcommerce.com/mesa\";> 
                     <mesa:sql>SELECT * FROM MBX_MAILBOX</mesa:sql> 
                     <mesa:pool>mysqlPool</mesa:pool> 
                     <mesa:result_name>result</mesa:result_name> 
                     <mesa:row_name>row</mesa:row_name> 
                     <mesa:query_type>SELECT</mesa:query_type> 
                </mesa:LightweightJDBCAdapterQuery> 
         </soapenv:Body> 
    </soapenv:Envelope> 
 
I am using the xalan-2.7.0.jar and xerces-2.7.1 jar. I try to do a unit
test of this method using the following code snippet, but still getting
the NullPointerException:
 
  DocumentBuilder soapDocumentBuilder =
DocumentBuilderFactory.newInstance().newDocumentBuilder();
  Document soapEnvelope = soapDocumentBuilder.parse(new
ByteArrayInputStream(SOAP_MESSAGE.getBytes()));
  Element envelope = soapEnvelope.getDocumentElement();
  Node node =
WSSecurityUtil.findElement(envelope,"Body","http://schemas.xmlsoap.org/s
oap/envelope/");
  System.out.println("Find node with name:"+ node.getLocalName());

Is it a bug or I am doing something wrong here? Any help will be highly
solicited.
 
regards
Abanindra