Northstar 567 Won't Talk to Autohelm ST4000

[ozmike]

I have a Northstar Explorer 567 Chartplotter, and a Autohelm ST4000 autopilot, I have found online an owners manual for the St4000, and it says it accepts data from NMEA 0183 output Northstar uses APA, APB, BWR, GGA, GLL, GSA, GSV, RMB, RMC, VTG, XTE. attached is the data that the ST4000 works with, the Northstar manual says to use the white and yellow wires for NMEA output, I hooked these up to the ST4000, switched them round, but it does not work, have switched on NMEA output, and enabled all the output codes, but with no result. before I spend the money to get someone down to have a look, thought I would ask here first.