My onsubmit function is not working.

My PHP file has two forms. Both form tags have an onsubmit attribute that links to the same javascript file. The first form's onsubmit is working. The function being called by the second form has been simplified to this:

function UserDataCheck()
return false;

The form tag is

PHP Code:
echo "<form name='user_form' method='post' onsubmit='return UserDataCheck();'>"

Please help. This is driving me crazy! Earlier I was doing some data checking in the UserDataCheck() but I stripped all of that away to see if I could even use onsubmit to stop the user from submitting! NO SUCCES