Bravo NAV config

Not sure if this is the correct thread, but I have an issue with the Bravo NAV button.

I'm using the G1000 in the Aerobask Phenom 300 with XP12.

I have the Configurator settings as follows for Variable 1 and 2;

sim/autopilot/NAV and 

sim/GPS/g1000n3_nav

However, when I press the cockpit NAV button in flight, I get this DRT response;

My question is, how do I map the 2 white datarefs into the Configurator with numeric values, when its just a press button?

I'm not an expert at this, so any suggestions or help would be appreciated.

V1