NSM Wall Performer Error 64

I have a NSM Wall Performer that works great. I also have a spare cpu board that I changed out the battery and installed in the working jukebox but with this board I get an error code 64. I know it's not the machine because it works fine with the original board. Any ideas of what's wrong with this board or where I can send it for repair.

Errorcode 64

Kontakt zum CD Wechsler unterbrochen
Verbindungskabel zum Wechsler und Steuerleitung überprüfen; Control Unit oder Wechsler austauschen

Check the connection cable for changer and control line ; Replace Control Unit or changer. I don't believe it's cable or changer because if I put the original board back in it's plays fine. It's got to be something on the spare board.