OBD2 Communication

[Sterho]

I have transplanted an LS1 from a 2002 Camaro into my 1964 Buick Skylark Convertible. Everything is absolutely perfect and am extremely pleased with the exception that my check engine light is on. When I initially started the car, the light was not on, but then I made an exhaust change and forgot to reconnect my O2 sensors, thus throwing a code. I reconnected the O2 sensor but the light won't go off. I purchased an Innova 6030P scan tool and it powers up but won't communicate with the factory PCM. I have triple checked the data wire to the computer along with both grounds and power lead and everything is pinned out correctly. Has anybody experienced something like this before? The car runs fantastic but I need to find out what the codes are reading. Thanks in advance for any feedback.