First: New to the forums, thank you to all of you guys that have put in work to allow a complete newbie learn tons about making stuff. I'd never even soldered before, and now I feel like an old pro. Thanks so much!
So to business

I still haven't received all my parts yet, but I'm mostly there. I got this (
http://sudomod.com/wiki/index.php?title ... te_Display) screen in the mail today, and after modifying it to work with 5V it worked great with the composite output from an Xbox. But after I hacked off the RCA connectors and wired it up to the Pi I was getting zilch. I checked all the wiring with a multimeter and it was solid. After some trial and error and even resoldering wires to the RCA connector, it seems that I need a ground for my video wire. When retesting with the Xbox output, without the ground wire hooked up to the RCA connector the screen displays nothing, but with it, it works like a champ.
Is there something obvious I'm missing here? Do I need to give the yellow wire a ground to the Pi?