Garmin GPSIII data output

Evening all,

I'm trying to use a Garmin GPS III to provide the positioning signal for
my Cleverbox vario. I've set up the output as NMEA at a baud rate of
4800, no matter what I try, the vario still can't see the signal.

I've tried a master reset on the Garmin and my PC can see the unit,
upload/download waypoints but still no luck.

I spoke to Cleverbox who confirmed the cabling and plugs are correct but
still no joy.

Any ideas?

Cheers
Rob