You should run a Pix experiment with "A replayable Direct3D call strean, saved to file" and enter a file to save the experiment to. Then, run your app, and close it after you've drawn at least one frame.

In Pix, in the "Events" window, expand one of the frame nodes (Not the first or last, I'd pick one around the middle), and scroll down to your first IDirect3DDevice9::Clear call, then look for a call to IDirect3DTexture9::GetSurfaceLevel before that (Probably 2 or 3 lines before the Clear() call). Click on the GetSurfaceLevel line, then on the "Render" tab in the "Details" window. That should highlight the address of the texture in the "Events" window, and let you double click on it to show the contents of the texture, which is whatever is being drawn on the quad.

If it shows black, then you know that your render target isn't being written to for whatever reason. If not, you know it's something to do with the rendering of the quad.