While subscribing channels to systems using "rhn-channel" utility from the client system, it fails with error "Error Class Code: 37"

Issue

• While subscribing channels to systems using rhn-channel utility from the client system, it fails with error "Error Class Code: 37"
• While subscribing to channels with rhn-channel utility, receives error below:

        #rhn-channel --add --channel=rhel-x86_64-server-optional-6
        Username: xx-xx
        Password: 
        Error communicating with server. The message was:
        Error Class Code: 37
        Error Class Info: You are not allowed to perform administrative tasks on this system.
        Explanation: 
             An error has occurred while processing your request. If this problem
             persists please enter a bug report at bugzilla.redhat.com.
             If you choose to submit the bug report, please be sure to include
             details of what you were trying to do when this error occurred and
             details on how to reproduce this problem.