EA Generation of XML schema

[fmm]

I've been having some problems in generating the XML Schema out of EA.
I've got large reusability of classes in my model.
So, for a given package I can create a class diagram containing not just the local but classes that belong to different packages - No suprise - Standard EA class usage through links.
The problem is that the generated XML schema for a given package does not contain the classes that belong other packages.
What do I do to have the complete XSD file with all the classes involved in the package class diagram?