VS 2005 Retrieving an xml document from a service

I am using vb. I am trying to create a simple web service that returns xml that is being called from SQL server. If I return a simple string like "Test", it returns it. Whe I change that to return an xmlelement and then create an xml document inside the function and then try to return the xmldocument output.documentelement it returns Null even though the object is not null. I am new to this, so go easy on me.

Thanks