I can't run HR in DirectX 11

[Conradsky]

Hey guys,
I've already finished the game using Directx 9, it runs perfectly fine. Now I want to have another playthrough and I'd love to actually see what the game looks like in DirectX 11 and if it'd run smoothly on my computer. The problem is I can't run the game using it, even though my graphics card supports DX11. What I mean is, the DX11 option is unavaiable, the box is greyed out. Any reason why? What can I do to fix it? :(

Screenshots:

http://i.imgur.com/H0oW6.jpg
Settings menu

http://i.imgur.com/ikiLB.jpg
Dxdiag

http://i.imgur.com/y26GZ.gif
My graphics card specification

[dennis10]

Another one of these unanswered.. I have a thread that is being ignored too! I too have an HD6870/directx 11 enabled, but it's greyed out and in red in the menu, nothing I do changes it. I've even changed the directx config in registry, but nothing!