I just bought an original version of RealFlight, V 1.20.71, to use on a 600 mhz computer. I installed the program and interface and when I plug my Jr 421 in I have no control. Am I missing some trick? It won`t calibrate in any of the modes either or show any input. Anyone have any suggestions? And yes, the transmitter does power up when I plug the jack into the trainer port.

Go to the calibration page and you will have to change the radio to interlink.
NEDYOB

Did that, still no luck.