Can anyone help?

I midi-cabled the Yamaha P90 piano (MIDI OUT) to Ty's MIDI-IN. I expected to be able to play the selected sounds on the Ty from the piano. It just doesn't work: all I hear is the piano sound of the P90 (of course, they are connected to a mixer and I can hear the Ty if I play it directly).

I order to make sure the cable is ok, I connected the TY as master (MIDI OUT) and the piano as slave (MIDI IN) and this way I could play the piano from TY.

Another tip: when playing songs on the TY and P90 on top, when I pressed P90's keys I could hear a second voice (strings) along the piano, yet that voice was not selected on the Ty nor on the the P90 as a second layer voice.

Can anyone help?

Thanks

Amelio