This problem could occur if Cisco Agent Desktop is installed on the Cisco Customer Response Solutions (CRS) server. Installing Cisco Agent Desktop on the CRS server is not supported.
To address this issue, perform these steps:
Install Cisco Agent Desktop on a separate machine and try to log in. Ensure that the Enable Computer Telephony Integration (CTI) Application Use option is checked for this agent on the Cisco CallManager.
To use the Enable CTI Application Use option, select CCMAdmin > User > Global Directory > Basic Search.
Search the username. Select the agent's user ID. Ensure that this user has the Enable CTI Application Use option checked.