To make final signed document field as mandatory

Hi Experts,

We are in Sourcing 10.0.

We have a business requirement to make "File Name" fields as mandatory (Final signed document) which gets activated after Executed phase.

I have tried using page Customization by adding dimension field to it, but its not working.

Also written script on validate event but that too also doesn't serving the purpose. As field is getting enabled after Executed phase.

Below is the code

if(doc.getCurrentPhase().getDisplayName(session).equals("Executed")){

  //if(other_phase.equals("Internal Signing") && current_phase.equals("Executed")){

//throw new ApplicationException(doc.getCurrentPhase().getDisplayName());

//throw new ApplicationException(doc.getCurrentPhase().getDisplayName(session));

if(!hasValue(doc.getFieldMetadata("SIGNED_DOC").get(doc)))

{throw new ApplicationException("please select file");

}

}

Can anyone help me on this how to resolve this.

Any leads would be of great help!!

Regards,

Geetika