RHEV3 : how to recreate default settings (without reinstalling rhevm)?

Hi,

During my testing, I decided to delete 'Default' data center so that to restart from start.

I'm able to recreate the 'Default' data Center but not the cluster! Entering 'Default' won't we accepted! however any other name is accepted! but in that cas, I'm unable to join hypervisor servers!

Some help will be appreciated

Regards