Diagnosis
In the "Assignment to Article Hierarchy" maintenance view, some of thenodes listed may be locked. To avoid inconsistencies, the rows concernedare locked, which means that the main assignment cannot be edited.

Procedure
If you want to edit one of these locked nodes, you can use transaction S
M12 to view the lock entries. In the Table Name field, enterWRF_MATGRP_STRUC. Here, you can find out who is locking the node and cancontact that person. Do not delete the lock entry manually as this couldcause inconsistencies.