I have used my Futaba 7CHP and works ok.

As you said it must be in PPM mode, you can set up a new model in memory called reflex to ensure it is in ppm mode. Also read you must select ppm mode then switch off tx and turn on again to get it to start in ppm mode. if the airplne memory you are using is pcm, just changing to ppm without restarting the tx it wont work in ppm mode (i believe, check your manual)

Also I have had problems with the plugs, so unplugging and repluging all plugs has fixed this.

I now just use a cheap 4 ch tx that came with an electric heli.

If it still wont work, try another tx if you can to see if it is the cord.

One last thing, after messing with settings sometimes the sim will not start just by turning the tx on, you must go to simulation - start simulation

cheers