I had a 98 a4 and it was a separate plug i forgot to plug in when i had it out. Hope that is your case i missed plugging it in and had many of them out.

 

No that's not it, I've messed with the little computer a few times trying to figure it out, checked the led lights on the board, they all work and the is 12v running to the center plug...I'm leaning toward the whole thing being shot

 

On ebay there is a company called BBA Remanufaturing they are based in the U.S.A. Massachusetts to be exact. They fixed my cluster for around $500 including delivery etc. I would recommend them as it will save you from having to recode your cluster again.