Unable to uninstall ZCM Primary appliance

Hi, I need to uninstall a 2nd Primary ZCM Server which was installed using the VMWare appliance image.
After running the command '/opt/novell/zenworks/bin/zenuninstall –x –s http://IPaddress_of_the_server:port_number -u username -p password -a'
I get the following message:
uninstallation of zenworks 11 sp2 from zenworks virtual appliance is not allowed. The wizard will exit now.

Any help please?