have a xml instance that references an XML schema. the XML instan ce voilates a xs:key constraint. cannot get the Xerces parser to complain

I use XML spy to build and test the XML Schema. It complains when a key
constraint is violated, but the Xerces Sax Parser does not. 
I have set the following features

http://xml.org/sax/features/validation
<http://xml.org/sax/features/validation> 
http://apache.org/xml/features/validation/schema
<http://apache.org/xml/features/validation/schema> 
http://apache.org/xml/features/validation/schema-full-checking
<http://apache.org/xml/features/validation/schema-full-checking> 
 
When I parse the XML instance, I see no Exceptions nor does my
ErrorHandler's warning, error or fatalError methods get called. 
 
 
Bill Riegel
LandMark Graphics
713-839-3388