ECM Port not working right

Details: 93 Trans Am, M-6, OBD-1, 383 Stroker with a lot of bolt ons

Problem: My ECM port is not comunicating with the cars computer
I'm not the only person who has had this problem.
I had the car at a garage last year and they couldn't get thier scaner to work either.
I'm trying to get my DataMAster Software to work.
My laptop is running Windows 2000 Pro and all ports are working.
Any ideas on what it could be?

Did you test the DLC for power? Mine is powered through the CIG/ACCY fuse.

DLC WHat's a DLC?

I have a ALDL cable that is powerd by the Cig. Lighter.
http://www.aldlcable.com/sc/details.asp?item=aldlobd1
That is working, I did the test on it with the computer.