Diagnosis
You have tried to change the valid-from or valid-to date for aparticipation ID which has already been settled up to &v21&.

System Response
In order to be able to identify the completed settlement later, thesystem does not permit this change.

Procedure
You can only change the specified participation ID after the &v1&. Ifyou need to make the change earlier for a settlement unit that has notbeen settled yet, you can assign the selected rental units a newparticipation ID.