Diagnosis
The Change planning function is being carried out by anotheruser. You cannot start it again for this plant and planning tool.

Procedure
RESET N1
Make sure that planning data processing is finished.
Exit the screen and call the function again (by choosingEnvironment -> Detailed planning (PFS)).
Start the Change planning function.
If this is still not possible, choose User list and delete thecorresponding entry (mode=1) from the lock table.