are you logged in when you test the page?
if you are logged in, and test with the email and username of the logged in user, it will override the server validation.
Make sure that you are not logged in when you are testing this.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.