[arm-allstar] Icom IC-2720h as Node Radio

[NV6V]

Greetings Group,

    Has anybody had success using an Icom IC-2720H as a node radio?
Setup: rPi, AriUSB fob, 6-Pin mini din cable to IC-2720H TNC interface
Success: COS detected, PTT triggering on Pi and showing on fob LED
Trouble: PTT not keying radio
Wiring to mini din socket (looking at socket, numbered left-to-right, 
top-to bottom):
1-audio in
2-ground
3-PTT
4-audio out
5-not used
6-COS

Thanks!

Andy, NV6V