Supperrior1

Hello, I'm not new to cars just Mercedes. I have 2009 E350 with the Command Navigation radio. The original was working fine but the LCD screen was washed out and no color. So swapped a perfectly working unit with it out of identical vehicle. Everything works perfectly except the radio is stuck on 1 station and underneath it say no service. I googled and checked the fuse, witch was good. Went into engineering mode and found the status of the radio antenna amp was blank. Amp underneath status was on. Help me understand why this would be happening......please and thank you!