Windows Server 2012 & Backup Exec 2012

Hi, 

I'm having some issues installing Backup Exec 2012 on HP OEM Windows Server 2012? I am faced with this error " You cannot install a Backup Exec Server or remote Administratior on a Windows 8/Server 2012 computer. 

Ive searched a load of forums and they all indicate that it is compatibility issues. But I dont understand as I have installed Backup Exec 2012 version 14.0 on Windows Server 2012 Standard before. 

The only real differences between the installs is, the successfull install was installed using CD and the failing install i am using ISO which was downloaded. 

Can anyone shed some light on this at all?