SAP Message WP762 - Only reversed or rejected documents can be processed

Diagnosis
You have tried to reprocess an external document that has already beenposted. This would result in the document being posted twice.

System Response
The status of the external document was not changed.

Procedure
First reverse the external document to cancel the posting. If you wishto change the external document, only make changes after you haveposted the reversal. Then you can reprocess the external document.