Document does not exist (Message 06 619) in creation of PO

Hi All

Can any one help on this below issue:

The error is 'Document does not exist' on each item that was on that RFQ to wrong vendor.

That is because I sent them out on an RFQ with different vendor.

Now I wish to process and save the PO to correct vendor.

How do I get rid of those errors that do not allow me to save PO?

Thanks

Sada