I have a Dynapath 20, but it ought to be smiliar. Your system is doing what mine did when the cable pin wiring was wrong. Have you been able to download to this machine from something other than Bobcad? If not, you might try Hyper Terminal on you computer and see what happens. You can also get something called an RS232 mini-tester. Using that you should be able to diagnose if your computer is sending and Dynapath is receiving. You should also try to send a program from Dynapath back to your computer. If the control acts like it is sending and the computer receives nothing, your cable is probably wired wrong. Again you can use the tester to confirm data is being sent.