Custom script help - Fetching from purchase invoice to payment entry reference

Created this custom script in Payment Entry doctype. Also tried in Payment Entry Reference doctype.

cur_frm.add_fetch(‘Purchase Invoice’, ‘bill_date’, ‘bill_date’);

I’m not getting errors from this script but no results as well.

My intent is to be able to fetch Supplier Invoice Date in Purchase Invoice to Payment Entry Reference.

Any help?