Have you tried doing validation the way it's shown on the official
Struts 2 documentation wiki?
(Although the code shown at the link seems okay from a quick glance; are you certain you've put the files in the correct places?) If you're having a problem with a third party's code, though, your best bet is to ask *them*. If you're having a specific issue with *your* code and/or configuration then you need to post it.