While customizing rules in the Permission Manager, you might receive an error message saying:
For System Manager (or any other role) at level 2 (or another level) in Customer (or any other document) in row 8: Permission at level 0 must be set before higher levels are set.
Error message indicates problem is in the existing permission setting for this document.
For any role, before assigning permission at Perm Level 1 or 2 (and so on), permission at Perm Level 0 must be assigned. Error message says that System Manager has been assigned permission at Perm Level 1 and 2, but not at level 0. You should first correct the permission for System Manager's role by:
Or
After executing one of the above steps, you should be able to successfully add new permissions rules in the Role Permission Manager.