If you are using either the Alpha and or Bravo you will need to do one of 2 things for the GNS430/530 to work:

1) Make sure that the AVIONICS BUS 1 switch is set to ON

2) Remove the switch command in the setting for SET AVIONICS MASTER 1

IMPORTANT: If using BOTH together then the command is automatically assigned to switch number 17 of the Alpha and switch number 47 of the Bravo.