This message: "Warning: Purchase order (PO number) of invoice (Invoice number) has got nothing to be matched anymore. All pending invoices of the order may already be finished" displays when saving a supplier invoice, or clicking the matching button (which also saves the invoice) when one or more of the purchase order numbers that have been entered in the "PO number" grid, on the top left of the supplier invoice form, have been fully matched to other invoices. This could mean that the purchase order number had been entered incorrectly, or that a supplier invoice has already been processed for this purchase order. You can use the Supplier Invoice Extended View to search for invoices by PO number.
I hope this helps.
Replied: Jul 08, 2019
you can check Unmatched PO Receipts as of Date for this PO if there
is sufficient qty to match