Unique, key, and keyref

I have a schema (http://abstractgamers.org/xml/iago-report.xsd) that
imposes a couple of unique and key/keyref constraints.  I'm using
XML::Xerces (obviously) and have tried using both validator.pl and
validator-dom.pl included in the distribution (using --full_schema).  I
am attempting to validate an instance document
(http://abstractgamers.org/xml/iago-report-test.xml) but it refuses to
flag the duplicate "iagoid" attribute in the <player> elements.  The
Xerces documentation suggests that these constraints are supported, but
I just don't know what else to try to make that happen.  I would greatly
appreciate any help you could offer.

Many thanks,
Aaron