Strange, it works perfectly for me. What exactly are you hearing? Normal 12-edo tuning, or nothing at all? What version OS are you using? What version of Reaper? What version of PianoTeq? The AUi format should work, but try the VSTi format too, just to check. No need to configure PianoTeq, it should work with alt-tuner straight out of the box. Try Helm too, IIRC it works like PianoTeq, just one instance needed.