Cannot add a vCenter on Avamar 6.0.1

Hello,

I have 4 vcenter registered as client type VMware vCenter.

I deleted a 5th one (who had no VM attached under Avamar) and wanted to add another but after I deleted the old vcenter I cannot add any new vcenter because when I try to add a new client, the type "VMware vCenter" is greyed out in the dropbox. Any idea why and how I can solve this ?

Thanks for help.

Steph.