SAP Message WTADDI254 - Wrong reference specified to purchase order for additionals

Diagnosis
This request for an additionals IDoc is based on an automatically-generated purchase order for an additional. Thedata supplied (purchase order number &V1&, item &V2&) is not correct.

System Response
No additionals IDoc is generated.

Procedure
Check the parameters AddiBuyHeadID and AddiBuyItemNo.