BMW: error 26, ground cables, obdi

Question
i know this is not your expertise but just incase you know or if you know anyone who would know. please... i have converted my e36 4 cyl to a m3 S50 US version engine. we got the tranny, engine, dme and harness from 1 shop. now that we have installed everything when we tried to start the car it would not start. we got to errors, control-unit supply b+ and ews alignment. we used a gt1 to align it and it was successfull. according to the gt1 we should check the battery supply and grounding of the vehilce for error 26. we did that and the car still would not start. we double checked the ground cables of the harness to the body, engine to the body, and the connection of the alternator and starter. the battery is giving enough current. do you have any idea what else i have missed ot should look into? hope you can help as we have been stuck for the past 2 months now. :)

Answer
Tomas,
 You are correct, this is a little above my head, but what year vehicle do you have?  I am more proficient with the E30's (body style before e36) and have knows several guys who have dropped the S50/S52's into these cars.  The problem most of them ran into was the OBDI to OBDII compliance with their wiring harness'.  The only thing I could contribute would be to possibly try another DME into your harness, and see if it changes anything.  when you changed the harness, did you splice it into your harness or pull your harness away and install the whole M3 harness?  That could have an affect on things.  Seems like you have a nightmare on your hands, and it doesn't look good.  
 I would try www.e30tech.net, there are several guys who have dropped these engines into the E30, and I'm sure they have run into the same problems you are.  Ask if any of them have seen these issues and know how to fix them.
 Good luck,
 Josh