Field validation failed using script trigger

Hello I have been attempting to create a script to disable/enable mandatory fields with some success, however the form now makes these fields come up with a validation error which I have been unable to rectify.

if  (NSFin.rawValue == "0") {

this.mandatory ="disabled"; }

//make field optional

I am now getting the error "POBU Validate Failed" with all four fields having the same result.  Would the script reseting cause this problem as this hadnt happened previously?

I can provide the form if that would make it easier to resolve.

Thanks!

else

{

this.mandatory

"error";

}