GTR 20 as comm 2

Obviously missing something in the G3X manual. I'm wiring my RV7A panel. 2 GDU 460s, 1 GTN 650 as comm 1, GTR 20 as comm 2, and my GMA 245 audio panel. 2 Ray Allen stick grips. I have great comm 1 through the 650 and PTT on the left stick and great intercomm both headsets. GTR P2001 pin 15 shows N/C. How is the right stick communicating with the rest of the system?
Thanks in advance!
SteveL

The GMA 245 has inputs for both the pilot's PTT on J2401 pin 34 and the co-pilot's on J2402 pin 33 and takes care of sending the output to the GTR 20 P2001 pin 17. The GTR 20 P2001 pin 17 is for both the pilot and co-pilot's PTT.