Truck Forums - Now my 4x4 won't work

Help!! Last week I pulled the front drive from my 2005, 2500HD, 6.0, 4x4 to remove the oil pan. That being done I put rod bearings, oil pump and timing chain set. That went well, when done I put everything back together. Then went up top and replaced the belts, knock sensors and harness, with that done, put it all back together. The engine fired right up and runs great, I again have oil pressure. Idle oil pressure is 45 to 50 lbs. Now for my problem, I now have a warning telling me to service the 4x4, I have double checked everything and everything is connected, electrical included. The 4x4 worked just fine before I tore it down. What could I have possible done or missed??????