xmlns disappears

[Michael]

Hello,
I have a Doc-Lit service with an operation can accept a type
containing xsd:any. This is intended to allow the service to receive
any document (from any namespace).

e.g.

<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>
<sendDoc xmlns="http://ns1.namespace.com";>

<MyDocument xmlns="http://ns2.namespace.com";>
    <a/><b/>
</MyDocument>
</sendDoc>
</soapenv:Body>
<soapenv:Envelope>

I need to serialise the body element as a string (which I do using 
DOM2Writer.nodeToString). However this serialised version does not
contain the xmlns attribute. e.g. it would appear as:

<MyDocument>
    <a/><b/>
</MyDocument>

This is causing huge problems since the namespace is essential for us
during later processing...

Any suggestions?

Thanks,
M