Customizing Form "VendEditInvoice"

Hi All, thanks for reading my question.

In Accounts payable - Common-Purchase orders - All purchase orders

In form "VendEditInvoice" i added field "PurchAddress" and i realize field"PurchAddress" to view address of purch that have name as "PurchName" shown.

And :  I used VendInvoiceInfoTable and LogisticsPostalAddress table to get that address but it is not correct. it is not address of purchase.

How to get that address??

Thanks All so much.