you also need to make sure you supply a +12V to the steering controls as well.
I hooked mine up a long time ago so I am not exactly sure, but the instructions where a little fuzzy on that part.
The stock head unit supplies +10V to the the controls and if you follow the direction with the SWI-PS it leaves that part out. You need to find that +10V wire on the stock harness and hook up a +12 (you can't do +10 anymore without the stock headunit). Then you should be able to program it ok.
The stock system works (at least on my 2005) worked on a +10V reference and a series of resistors to tell the head unit the button you pushed based on volatge drop.