What version of Seam and what version of the hibernate-validator jar?
Our project had the same problem with the hibernate libs bundled with Seam 1.2.1GA. We fixed by ditching the bundled hibernate libraries and using newer ones. Hibernate Validator 3.0.0.GA supports the style of validation you seek.
I'm not sure what version of hibernate validator is bundled with later versions of Seam.
Hope this helps.
Seam 1.2.0GA and JBoss-4.2.0.
I downloaded hibernate validator 3.0.0 and will now use that.
Thanks very much.