96 chevy SBSC with L31R

I have performed the repin for the 0411 per the spreadsheet from Lextech. I just got my flash/tune from Blackbear, and am trying to install thru OBDII port using an Autocal. I keep getting a $0281 error code when trying to load the tune to 0411 ecm. When I go to Prog, it says Checking, goes to 100%, pauses about 3 seconds and says $0281 error code. BB says that is a communication error code, and could be issue with OBDII port wiring or ignition wiring. The ignition seems to work properly as the key buzzer comes on, run position lights up the gauge cluster, and truck turns over just does not start. The OBD port is powering my autocal.

I've verified my cig lighter is operational, pulled the AM radio fuse (and radio batt fuse), abs fuse, and I double and triple checked the wiring diagram I received from Lextech. Still getting the error code.

I will admit, I had the blue ecm connector installed upside down on the 0411 initially while trying to flash the tune. I have since corrected this, but still getting 0281.

I also have an Autopage aftermarket alarm with a starter disable relay. Would the alarm possibly be causing an issue with 0281 ?

Please help.

Thanks,
Mike