Create GBPA and generat Standard PO > cursor on PO Line Level > (B)Catalog displayed as GRAY

Hi Experts,
SEV.1 issue, any points from yours are apperaciated.

PROBLEM DESCRIPTION:
-----------------------------
1. create GBPA, save and approve successfully.

2. generated Standard PO which reference GBPA.

3. Put the cursor on Standard PO Header level, (B)Catalog could be clicked as expected.

4. Put the cursor on Standard PO Line level, (B)Catalog could NOT be clicked, and display as GRAY.
-----------------------------

***Expected the (B)Catalog on Standard PO Line level could be used as expected.

Thanks,
Joy