Backup of DMZ server

I have a server in the DMZ. It is not on the domain. I get an error msg access denied when I try to backup this server. The client netbackup services are running under the system account. I created a netbackup local account, added the account to the administrators and backup operators group. I have the netbackup client service and the netbackup legacy client service run under the nbackup account. But the netbackup legacy network service does not start under the nbackup account. The backups are failing due to access denied.