Hello Murali,
Problem might be you are not having the authorization, follow below steps to perform the check.
Open two SAP sessions in the system. In first session give transaction LC10 and enter the Name of the database connection->Livecache monitoring with DBA Cockpit, it will give you an error message as you said.
Now in the second session go to transaction SU53, where you will find the authorizations, check with your User management team and ask them to assign those missing authorizations to your user ID.
Regards,
TP