I'm using a Cisco Unified Communication Manager 184.108.40.20600-18 installed on VMWare ESXi 3.5 system Server. I have a default based license as 150 devices. I have used all 150 licenses and i try to delete some devices ip phones to have free license that i can test for another device but i cant, an error said that: Error occurred. One or more record did not get deleted.  Licensing checkin failed (checkin count is greater than checked out count).
Could you be pleased help me?