Manual "Closed" PO status auto change to "Open"

Product: Oracle E-Business Suite R12

Application : Purchasing

Oracle Applications : 12.2.7

Hello

Scenario: PO Order quantity 10, SRN Qty 9, Invoice matched to SRN Qty 7, hence SRN available to match with invoice is 2 Qty.

Step1: PO closed manually. PO status changed to "Closed"

Step2: Invoice matched with SRN 2 Qty.

Issue: PO status automatically changed to "Open"

Business Requirement:

Either system should not allow to close PO manually if SRN is available to match with AP

Or system should status should not change automatically to "open"

Please help

-Pankaj