I Cann't choose Certificate Authority Enteprrise ? Why ?

Hi all ,

I have a StandAlone Windows 2012 Server joined in a Mixte Active Directory Domain Windows  (2003 and 2008R2 DC).

The Forest and Domain Level are Windows 2003.

So When i need to choose the type of AC (Enterprise or StandAlone) during the configuration i can choose only Standalone not Enterprise.

Of course,  I try  to do this configuration with an enterprise domain account, do you have any idea ?

I 'm waiting for yours replies : I 'm going to try on a 2008 R2 server perhaps it will work better ....

Thank a lot.