SEP 11 Clients Not Upgrading from SEP 12 SEPM

I have a question?

I have migrated a number of SEP 11 Clients to our new SEP 12 SEPM.

Some Clients upgrade easily and reboot, but different groups do different things, like some won't upgrade at all even after the auto upgrade is loaded. I verified that.

I know the MS FW or SEP FW are turned off. UAC is off. 

Any suggestions, on what I am missing and why they are not upgrading?

Any assistance would be appreciated.

Thanks,