Just a little note to all of you who might be experiencing this issue, a couple ideas to first ponder.
1) If you have a 1.6 xbox, make sure you have rebuilt your LPC properly, all 4 pins rerouted. Also, 1.6 xbox's need an alternate 5v power lead. Check this with #2 below.
2) x3 should have 2 blue led's showing from the chip itself. This shows the chip is being properly powered.
3) pin headers to which you are plugging the black wire into have VERY small pins which have been known to easily bend. Check carefully to ensure that you havent bent any pins inside the headers.
4) Slow down, make sure you've read the tutorials CORRECTLY and know what you should expect.
5) solderless adapter? make sure your pins are making good contact, and that your chip is properly powered and seated.
6) If all else fails, inspect your solder work. Any cold (dulled looking) joints? have you broken any traces? Best to break out your multimeter and test continutity across your solder points, and continutity across wire connectors.
7) To state the obvious: 1.0-1.5 xbox's will have 3 wire headers attached (d0 bundle, eject mod, front panel) while 1.6's will have 4 (these 3, plus alt. power)
Good luck, this little bugger drove me frickin' nuts..
P.S. All it took me was to triple check everything and give allmy connections a good wiggle..