Diagnosis
The scheduling agreement item, &V1&, for which you want to maintainschedule lines is planned in the Advanced Planner and Optimizer (APO).This is configured in the additional data for the scheduling agreementitem in the field Ext. planning.
Therefore, you cannot maintain schedule lines in the standard system.

System Response
If you change the schedule lines for this item, the changes are notautomatically copied to the APO System.

Procedure
Make your changes in the planning APO System.
If you want to make changes, you should do this in the planning system.
Otherwise your changes are overwritten the next time that schedule
lines are adopted from the APO System.