I don’t own the RealSimGear G1000, so I may not be of great help, but just to get the ball rolling with some questions so that others who own this might be able to help more:
What exactly doesn’t work about it? The knobs don’t do anything?
Does it not work with any aircraft, or does it just not work with the Cockspur Citation C510? Does it work with the default Cessna 172 G1000 or the Beech Baron?
Just a guess, but the OP may need to get a 3rd party driver for it, in order to be able to access the simvars on the 3rd party plane. I use Spad.next with my RealSimGear GNS530. It works great. I don’t even bother with the RealSimGear interface application; I uninstalled it.