Backing up Hyper-V host is in a workgroup

Hey guys! I need your help:

 

Is it a requirement that Hyper-V host is in a domain in order to back up the virtual machines that reside on it, if the Backup Exec media server is in a domain?? the Hyper-V host is in a workgroup.

 

I already installed the remote agent manually on the Hyper-V host, because I was having trouble to push the installation.  Now, the remote agent is installed and published to the media server, but the Hyper-V host is not visible in the backup selection list.