onsubmit event to mark column within table as required based on outcome is not working in webform

Summary:

In my PCS application, I have created a onsubmit event for a webform which will mark a column within a table as required based on the outcome of form like APPROVE, REJECT. Even though event triggers but it fails to mark required and stop submit action if not populated.

My form is attached to a human task

My web form and the field on which adding the onsubmit event

below is the event screenshot

Please help, why its not working

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):