Persistent Class to XML Schema

Primary tabs

Ensemble, XML

I have a class extends %Persistent & %XML.Adaptor

It has 100 properties for example

Now I do intend to create a xml schema that I can import in Ensemble->XMLSchemas 

I did try to use XMLExportToString and %XMLWriter.GetXMLString

but didn't give me a proper schema. May be I am missing some small step

Can someone pls help