My validation callback isn't getting called. :(

[eluser]Kinsbane[/eluser]
I have a function that registers a user. The function when run needs to check the $_POST data and make sure the chosen username and email address are not dupes.

The user_duplicate_check callback gets called just fine, and works as it should.
However, if I input a unique username, but use a previously used email address, the form goes through and I get the registration email.

I looked in the logs for any troubleshooting help, but there was none. I put a die() message in the email_duplicate_check function before it ever did anything, just to see if it gets called, and it doesn't.

What's the best way to see that a callback function gets called? Can I only use one callback function when validating form data?

I'd post code, but I don't know which code to post, heh!