DC failure when shutting down

hi,

I had a DC, with Server 2008. I added a new physical server, with Server 2012 and moved all fsmo roles to the new server. replication is doing as it should(all dns entries are being replicated, and users created in one Ad is replicated). however, when I shut down the old DC, the new DC does not work. I get the error '

however, when the old DC is online, everything works fine. I have also tried to do a dcdiag /fix and got the following as attached.

any help will be much appreciated.

PS: both DC has their own ip as primary dns..and I checked in the global catalog server, that the new DC is the gc.I also checked in the dns that the entry _gc is indeed the ip of the new server.