SAP Message REBPBP045 - Role &1 [&2] is not allowed (does not agree with technical role &3 [&4])

Diagnosis
You assigned a partner with the role &V1& (&V2&) . Thisrole is not based on technical role &V3& (&V4&).

System Response
It is not possible to assign the partner.

Procedure
Select a different partner or enter a different role for the partner.