Q: Problem using G-player with Logic Pro X

I recently changed over from Logic Audio Platinum 5.1 to Logic Pro X. I opened an old file from 5.1 and it opened beautifully in Pro X. I can run G-player through the  Logic Pro X. I have a G-player trombone put onto a new channel/track (left side channel strip). I can play this trombone using my keyboard controller. But - when I pull a previously recorded music track onto the trombone channel, the previously recorded music track is mute - will not play. What adjustment do I need to make to get the notes on this previously recorded track to play the new G-player trombone sound?

The old version of Logic 5.1 would easily and simply play any track moved onto any instrument voice. Logic Pro X will not. Why, I need to know?

Thank you,

Robert