Invoice not blocked from posting even if final inv indicator is checked in

Hi,

We have set "No Futher Invoice" Indicator on SRM PO so that no Invoice is posted in ECC, but still able to post an invoice. We didn't find any fields on SRM PO to block the PO Line Items, and we don't want to delete the PO line item because of reporting issues.

Have any of you faced the same Issue? How can we resolve this issue on blocking PO Line Item or Block complete PO so that NO INVOICE can be posted.

Your help is really appreciated.

Thanks

Vijay