Any LX5000, SeeYou Mobile & Downloader users ...

I'm new to both of these products, and I'm a bit perplexed about a
connection question.

My iPaq has a cradle added to the glider by the previous owner, who like
myself, ran WinPilot. The iPaq receives the GPS's NMEA stream from the
cradle's connection to the LX5000. Works great, no problem. I expect SeeYou
Mobile, which I'm now starting to play with, will see the same NMEA stream
on the same comm port and be just as happy.

But when I tried to use the "Downloader" program on the iPaq in the same
cradle, it couldn't establish a connection with the LX5000, and some stuff
I've seen on the web talks about using a null modem cable adaptor and the
LX5000's other 5-pin connection on the instrument panel. Why
wouldn't/couldn't Downloader use the same connection that the GPS stream
uses? Is it simply a matter of that connection being dedicated strictly to
GPS data?

-ted