New User question - no Sound with iPad

I have new version of IPad and Yamaha Clavinova CLP-745. I downloaded the free version of Pianoteq to the iPad. I bought 2 cables. First one out from iPad that has a standard USB on the other end. The other cable is connected to the first cable and goes ToHost connection on Clavinova. I updated Midi connection off from Clavinova. And on Pianoteq I chose Clavinova as the Midi input.
When I play Clavinova the keyboard on Pianoteq screen is activated. The same keys are played. But there is no Sound on Clavinova. What should I do?