Rebuild Indexes Error - Object has no schema locks

I received the following error when trying to rebuild indexes on an 10.1 enterprise geodatabase:

Could not rebuild indexes for dataset egis93.SDEDATA.WTR_INVENTORY/egis93.SDEDATA.WR_WaterBodies.[Object has no schema locks.]
Failed to execute (RebuildIndexes)

Not sure where to look to correct this - suggestions welcome.