spacewalk is not working

Getting the below error when trying to add or remove any channel from client server to Redhat satellite server.
Please help me how to get out of this error?

[root@rlt03test ~]# spacewalk-channel --remove -c bby-rhel5-x86-64-fy15-pci-r1 - -user xxxxxx --password xxxxxxxx
Error Message:
You can not unsubscribe 1000045176 from base channel bby-rhel5-x86-64-fy15-p ci-r1.
Error Class Code: 72
Error Class Info: You can not unsubscribe from base channel.
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.

Regards,
Abhishek
Unix Team