Windows server2012 + Hyper-V + Windows7SP1 VM can work with RemoteFX7.1 ?

I have 2 kinds of win7sp1 VM:
 1. Install Win7sp1 by creating a new VM, then install a win7sp1,  ==> the Client window will display with 1024x768 
    then enable RemoteFX                                           ==> the Client window will display with standard VGA
    
    Then I use a win7sp1 NB to link to this VM, the VM didn't run with remoteFX protocol.(client very slow)
    
 
 2. Install win7sp1 in Winserver2008R2 Hyper-v's new VM, then copy xxx.vhd file to Winserver2012 server as a new VM.
    before enable RFX   ==> the Client can show and and be link by my NB with win7sp1.
    
    then Enable remoteFX==>the Client window shows "video remoting was disconnected"...., 
                           while my NB cannot link to this VM anymore.
    
So I have a guess:  Winserver 2012+hyper-V cannot support Win7SP1's remoteFX ?