OpenSAML user discussion

Hi,

I have been working on a research project that use SAML v2. Currently, I have 
created a simple SAML assertion using openSAML and try to bind the SAML 
assertion into a SOAP header. However, an error occured states that:

>> org.w3c.dom.Element is an interface, and JAXB can't handle interfaces.

I am using Glassfish v2 to build my web service and JAXB for XML binding. My 
SOAP and Marshal code is below:

//Create a SOAP Message
SOAPMessage message = smc.getMessage();
SOAPPart soapPart = message.getSOAPPart();
SOAPEnvelope soapEnvelope = soapPart.getEnvelope();
Name wsseHeaderName = soapEnvelope.createName("Security",
                        "wsse", WS_SECURITY_NS_URI);
if (soapEnvelope.getHeader() == null) {
       soapEnvelope.addHeader();
}
SOAPHeaderElement securityElement = 
soapEnvelope.getHeader().addHeaderElement(wsseHeaderName);


 // marshall Assertion into SOAP Header
                MarshallerFactory marshallerFactory = 
Configuration.getMarshallerFactory();
                Marshaller marshaller = 
marshallerFactory.getMarshaller(assertion);
                Element assertionElement = marshaller.marshall(assertion);
                securityElement.appendChild(soapPart.importNode(
                        assertionElement, true));

Does anybody has an idea on how to solve this problem? Any help will be 
highly appreciated.

Thanks,

Rick