E_FAIL D3D11CreateDevice

ID3D11Device* md3dDevice;
ID3D11DeviceContext* md3dImmediateContext;
D3D_DRIVER_TYPE md3dDriverType = D3D_DRIVER_TYPE_HARDWARE;
HRESULT hr = D3D11CreateDevice(
            0,                 
            md3dDriverType,
            0,                 
            D3D11_CREATE_DEVICE_DEBUG, 
            0, 0,              
            D3D11_SDK_VERSION,
            &md3dDevice,
            &featureLevel,
            &md3dImmediateContext);ID3D11Device* md3dDevice;

当我包含D3D11_CREATE_DEVICE_DEBUG标志(没有标志就可以正常工作)时，我从这个函数中得到e_fail。我认为这与我的调试运行时有关，所以我按照这个线程中的说明重新安装了dx sdk:什么会导致D3D11CreateDevice()与E_FAIL失败?但这并没有解决问题。

我在dxdiag中仍然看到零调试级别:

--------------------
DirectX Debug Levels
--------------------
Direct3D:    0/4 (retail)
DirectDraw:  0/4 (retail)
DirectInput: 0/5 (retail)
DirectMusic: 0/5 (retail)
DirectPlay:  0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow:  0/6 (retail)