Are you capturing a full stream, or only a frame? You could try to verify that the buffers were properly created by calling the GetDesc member function and verifying that the object allows you to actually access its data. That way if your graphics tools are not catching the second buffer creation then you can still rule the creation part out.
Do you also have the debug runtime enabled? If you enable it, then any obvious misconfigurations (like a potentially missing buffer) will get printed to the output console.