[TG] AIS not available on second unit (C-series Classic over Seatalk)

Hello:

I have a C-80 at my internal helm with AIS connected via NMEA to the unit - it works fine.
I have just installed a c-70 at the helm and connected power and the SeaTalk. Everything works on the helm unit (gps, compass, wind, etc.) but not the AIS. The Icons says AIS is not working.

I expected the AIS data to be hared over the seatalk network like all the other data - is there any way to do this, or do I need another connector to the helm unit's NMEA?

(both units have the latest firmware installed)
Thanks

IcarusBop