SAP Message 2054ALE021 - Assignments to WBS element only allowed in the WBS master system

Diagnosis
You have tried to assign the WBS element &v1& to the current object,although the WBS element was created in another master system.

System Response
INCLUDE NA_ALLG_NOVERARBEITUNG OBJECT DOKU ID TX

Procedure
Assign the object a WBS element, whose master system is the currentsystem.