From what I can tell from googling this problem, it's not the DX11 software on your computer that's the problem, it's the DirectX hardware support on the GPU that is lacking...
The is a common response to people reporting this problem...
Typically caused by not having the minimum directx support in the GPU. For NVIDIA GPU's. DirectX10.0 support is required.
I know the card advertises that it does have full DX11 support.
The 520 GT is a very low end card. With all due respect, if you want to play current games I'd suggest upgrading to a more capable card, perhaps a 560 for under $200