The box indicating that this domain controller is the last controller for the domain is unchecked. However, no other Active Directory domain controllers for that domain can be contacted

I have 2 domain controllers running 2003 server, server1 and server2. I ran dcpromo on server1 and removed AD and removed him from the domain and disconnected from network. I then added a 2012 server with the same name and IP address server1 with no problem. Replication from sites and services work fine on both controllers.
The new 2012 server1 is GC. I transferred all FSMO roles to server1. Again no problem and replicating using sites and services. AD on server1 is populated correctly.

Now what I had intended on doing was a dcpromo to remove server2 from the domain so I can then add another 2012 server. That is when I get the: "The box indicating that this domain controller is the last controller for the domain is unchecked. However, no other Active Directory domain controllers for that domain can be contacted.

I have DNS installed on both servers and both look good with replicating there. Strange thing is when on the 2012 server within DNS if I right click and connect to another DNS server I can add server2 just fine but from server2 adding server1 it tells me it is not available.

Help please!