we have compatibility issue between the antivirus and new MS server 2012,
We are unable to install Symantec 12.1 on windows server 2012,
you should be using the latest version of SEP i.e. SEP 12 RU2 which is compatible with 2012 server.
check this system requirement link
http://www.symantec.com/docs/TECH195325
Windows Server 2012