How to allow print only if student paid in the education module

ERPNext
1

what i want to do is disable print from student applicant document if student still has outstanding balance. i tried this script but nothing happens.

> frappe.ui.form.on("Student Applicant", {
>   onPrintDocument: function(frm, doc, ev) {
>     // Get the Fees document
>     const feesDocument = frappe.get_doc("Fees", frm.doc.fees);
> 
>     // Check if the outstanding amount is 0
>     const outstandingAmount = feesDocument.outstanding_amount;
>     if (outstandingAmount === 0) {
>       // The outstanding amount is 0, allow printing
>     } else {
>       // The outstanding amount is not 0, prevent printing
>       frappe.msgprint(
>         "Fees payment not received in full. Cannot print."
>       );
>       ev.preventDefault();
>     }
>   }
> });