[jQuery] JQuery validate remote call allows form submission before call returns

I believe I'm having a sync issue with the remote validate option.
The sample form can be found at
www.apylon.com/dagangnet. Basically, the issue is that the captcha is
set up for remote validation, but before
the result can be returned, the form can be submitted. How do I force
the form to not submit until the value is returned from the remote
call?
Thanks