void D3D11Rendering::initD3DDevice()
{

	D3D_FEATURE_LEVEL  FeatureLevelsRequested = D3D_FEATURE_LEVEL_11_0;
	UINT               numLevelsRequested = 1;


	HRESULT hr = E_FAIL;
	D3D_FEATURE_LEVEL FeatureLevel;

	hr = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, D3D11_CREATE_DEVICE_DEBUG, NULL, 0,
		D3D11_SDK_VERSION, &swapChainDesc, &swapChain,  &deviceDX11, &FeatureLevel, &deviceContext );

	if(FAILED(hr))
	{
		return ;
	}
}

I guess it was it ?

It still doesn't work

It is ever created i initialized it in the constructor, there is no problems with that.

vertexGBufferLayout has no value (null pointer), I tried with DXGI_FORMAT_R8G8B8A8_UNORM and vertexGBufferLayout has still no value, I tried also by removing all lines concerning colors in the vertex shader and this code from C++ code :

layout[3].SemanticName = "COLOR";
layout[3].SemanticIndex = 0;
layout[3].Format = DXGI_FORMAT_R8G8B8A8_UNORM_SRGB;
layout[3].InputSlot = 0;
layout[3].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
layout[3].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
layout[3].InstanceDataStepRate = 0;

And it still doesn't work

I tried to put D3D11_CREATE_DEVICE_DEBUG and my program crashes sooner in my code at a place where it usually doesn't crash. And I have no more messages in the output than before.

If you are using vs2010, a recent update caused a crash (on device creation if I remember correctly?). You can fix that by installing the remote vs2012 debugging tools (free). see here: http://blogs.msdn.com/b/chuckw/archive/2013/02/26/directx-11-1-and-windows-7-update.aspx
You really should make sure you get the debug runtimes working, it's really helpful, definitely worth the (minimal) effort to setup.

I get screen dimensions and affect it then.

For vs2012 tools, thanks i'm downloading it, I come back then to tell you if it works or not.

It works, I forgot the semantics which were in output from the vertex shader.

And I can now use the directx debug runtime.

Thanks