Can not Edit Bill for backordered Items

Can not Edit Bill for backordered Items

Hello ,

We did back order for some items and after item received we Converted the PO to Bill successfully.

We made a mistake in Bill Prices and we want to edit the Bill but we get the Below Error.


((   Only backordered items are allowed in this bill.  ))


All items in our Bill have been Backordered and fully received.

Pls advise how to solve the error and edit the Bill.