How to Clear red border for a mandatory field

  On exit event I am using the script below to clear the red mandatory border around the field:

if (IssueDate.rawValue !=null)

{IssueDate.mandatory = "disabled";

}

else

{ IssueDate.mandatory = "error";}

I am using the same script for a field in a repeating row of a table

but does not work!

What I am doing wrong?

Thank you for your help