Diagnosis
A plant group which is assigned to the promotion was deleted in theclassification system.

System Response
You cannot expand the plant group and therefore you cannot carry outfollow-on processing.

Procedure
Determine the assignment concerned in the "Assign plant group" view (anentry is missing there in the "Plant group" column) and delete thisassignment.
If necessary, create a new plant group and assign this to thepromotion.