Deleted PO Approval Notification Accidently, now cant approve Draft. (2007)

My Customer accidently deleted an approval notification. The PO displayes in the Document Drafts report, but when the user drills down into the draft to add it, they get a message: "An authorization for this document has allready been sent. Document can not be added unless this authorization process is completed."

I have two users who can approve this documet, with a required segnature of 1 user.

Any suggestions?

thanks