Diagnosis
Only a revised version exists of the selected cluster. Since thisversion is being blocked by another user, you cannot access thisobject. The lock could be for a limited time (e.g. the user ismaintaining the ojbect at the moment) or it could be a permanentlock against changing the revised version.

Procedure
The only way toremove the lock is for the user under whose name the lock is entered toactivate the revised version or to explicity release the revisedversion for maintenance by other users with the 'Unlock' function.