Jay,
You did NOTHING wrong - either we have a bad cable or a bad box at the 6-pin connector and would not allow the video signal to come through. I used a video splitter and ran it to the external A/V port of the passenger monitor; not pretty but at least it works.
Hopefully the brake line kit will arrive this week so we can take care of it next Sat at Steve's house again, assuming that's still the plan!