I have done what you said (see photo). The problem I have now is that I can turn the lights on an off, but they don't dim/brighten as they should - is this likely to be because of incorrect wiring (of the brown wires - both are in the socket with the X symbol), or because of a faulty lightswitch (it's new)?
By the way, the instructions say to wire the ground cable to the faceplate first, then the backplate - is there any danger in doing it backplate first, then faceplate?