[jQuery] Jquery validation remote problem

Hi,
I'm using Jquery.validation to remotly test if an e-mail is already
in use, it works fine, but... if i do a remote check, it returns the
correct response e.g. "someone@abc.com already in use" but when i
click on the field, and then somewere else the message changes to
"filename.php already in use".
Try is on http://www.red187.nl/milk/
This only happens when i set the return vale to 'false' in th eremote
file, when i return a message there is no problem...
Can someone help me please?