Tunercat connection issues

I have a 95 z28 that has the obd1 computer, but an obd2 connector from the factory. When ever I try to do flashread with tuner cat, the com port will not open. We use the same program on a 91 with no problems, and a 91 vette as well. I've tried it in DOS and windows with no luck. Why can't the laptop communicate with the pcm?

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James
95 Z28 M6
-355 forged 11:1 motor and Nitrous Works Wet kit 125 shot :)

Are you sure your cable for the 95 is good? I had the same problem and it turned out I had the ground wire soldered incorrectly in my homemade cable. Good luck.