Is the VXML2.0 Schema Definition correct?

Hi.
When I try to validate the vxml.xsd schema using Microsoft XSDObjectGen 
I get:

"Error occured: Schema Validation Error: reference to undeclared 
substitution group affiliation. An error occured at 
file://(...)/synthesis-core.xsd, (372, 3)"

Thanks.

-- 
Pedro Fernandes
Finantech