2012 Mercedes Gl450 Air Suspension Issue - Rear Air Bags Not Inflating


I just replaced the entire air suspension system on my 2012 GL450. New air springs at all 4 corners and a new air compressor pump. Turned the key and the front air springs inflated just fine. rear air springs are not inflating. 40 amp fuse for the pump in the engine compartment is fine. 15 amp AIRMATIC fuse in rear is fine. Is there something I'm missin?