how to create win 2012 server virtual machine with vmware cluster running both ESX 5.1 and ESX 4.0

hello,

I had cluster running ESX 4.0 host, i have updated vcenter to 5.1 and added a new host running 5.1

when I try to create a new VM, it does not gives me option to choose win server 2012.

I tried disabling fail over etc.. but not help.

Any thought.

Thanks