To Approve PO at PO screen level after Double Click the PO number in ME28

Hi

I have been using ME28 for years and I was struck down by this request:

1. At the ME28 output screen, double click on PO.

2. At the PO screen, examine the PO details and click on APPROVE there. Then click on BACK

3. At the same ME28 output screen, double click on the next PO.

4. Go to step 2.

However, I have tried in the PO screen (after double click in ME28) and even go to CHANGE MODE, the approval icon does not appear. Is this standard SAP behaviour?

Thanks.