I agree with Andrea.
Just a note though. I had the same problem with Hunter, though for all sleep times and night wakings and not just naps. PU/PD did not work for him, and just worked to stimulate him. What worked for me was to sit in his rocking chair, and pat/rub his back but not rock. I gently weaned him from the rocking, then again with the patting/rubbing. Finally he took to pu/pd, and we are great now. It was a LOOOOOONG process though.
HTH