RemoteFx not working but videocard correctly detected

I have a windows server 2012 R2 with 2 Hyper-V guest operating system. One of them is Windows 7 Sp1 Pro and the other is Windows 8.1 Enterprise.

I want to use remotefx to connect to these guest os remotely.

I have successfully installed remotefx on windows 7 and it work without issue.

I did the same thing with windows 8.1 ( in hyper V I add the remotefx video hardware)

When I log into windows 8.1 I can see that remotefx video driver has been installed but it is not working when I connect with remote desktop.

Also if I try to connect to the windows 8.1 guest using the hyper-V, I can see the display just fine. It's not suppose to work when remotefx is activated and working properly.

Is there anything else I have to do in the guest OS so that windows 8.1 run using remotefx ?

Thank you