My Client receives a high volume of zero valued invoices relating to the scenario where faulty/damaged stock is replaced by a supplier and they issue zero value invoices for the replacement of the stock that is faulty or damaged instead of issuing a credit note and re-invoicing for the new stock at the normal cost. 

When a PO is created for the zero value stock, It is possible to process an invoice directly against the PO, however it is not possible to post the invoice to the invoice register to be matched later to the PO 

When attempting to add the invoice to the invoice register, and then match the invoice to the PO, it is not possible to post the invoice on the invoice register, you receive the error message "Posting without amount cannot be made"

My client needs to be able to raise these invoices on the invoice register so that they have a consistent process for their staff for processing purchase invoices.

If it is possible to post the invoice against the PO it should be possible to post the invoice on the invoice register as well.

Please can this be fixed so that these invoices can be processed via the Invoice register?