I had the same problem, wrote in, and he didn't have a clue, except he said that it might be the midi. I knew it wasn't the midi, so tried a different sampleset. It is working now. Not sure if that was the reason though.
pa4X 76 ,SX900, Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact