Additional Domain Controller fails.

I’m trying to add an additional domain controller for an existing domain, as a backup. When I try to install active directory to my new server I get the message: ‘The Domain “MDPLASTIC.com” is not an Active Directory domain, or an Active Directory domain controller for the domain could not be contacted.’

The old server has this server in the active directory. I can ping each server from the other.
I mapped a drive on the new server to a folder on the old server.

What’s the problem
Thanks, Pat