R5 -R7.0.2 server upgrade & submit button

This is a bit strange… any thoughts? This worked fine on an R5 server. A button with onClick calls validatefields() to check fields then uses $$Return to redirect users. The function is just (inherited this old Db!) in the form… not JS header or as JS script library, etc. Has something changed that would cause the form on submit (using the above) to appear to submit the return to a blank form. No form save…