I can tell you from our experience the failure rate on the cables is actually very low. Probably in the 2-3% range from the amount we've sold. The design is actually pretty good from the perspective of copyrighting the software. As Chuck describes, the cable has a proprietary chip under the shrink wrap that is encoded for the software. When the program boots up it handshakes with the chip through the USB port. If the cable is not there then the program will not boot up. I would strongly advise trying a different transmitter to see if this works. I have found some transmitters are not compatible (don't know why) but it's true. The trainer ports have basically three wires: a ground, a data transmit, and a data receive; just like a typical serial port. Even though a transmitter may work as the master transmitter when hooked to a student's buddy box, does not mean that it will work in reverse as a student buddy box. So if you follow me it might receive the signal from another buddy box but it might not be transmitting the stick signals out through the trainer port. This is exactly the case in a friend of mine's 8UAP radio. I have the EXACT same radio as he does and mine works fine. His does not and we verified that something is wrong with his trainer port. He can use his as the master for training students but he can't use it as the student transmitter. We checked for a broken wire on the inside but it looked fine so it must be something in the circuitry????
Anyway, Mike at Ikarus is definately the technical guy to talk to when all else fails. But again, try different transmitters first to be sure it's not the cable.