I thought I'd post this in case anyone else had the same problem as I did. Through a local car audio shop, I purchased a new Pioneer head unit AVH-4200DVD with the separate bluetooth module and a steering wheel controller by Axxess called the "ASWC". This is like the PAC SWI-PS except it has an "autoprogram mode". I am sorry to say I paid a premium at a local shop because I was too lazy to install it myself (wasted money. . . .).
The head unit is fantastic, but I had a problem where the "forward" or "next track" button on my steering wheel control wouldn't work. I called the guy that installed it and his proposal was, and I quote, "Try pushing real hard on the corner of the button, it's probably something wrong with the steering wheel control button." Stupid, incompetent, lazy crap. . .but I digress.
So to save my blood pressure from raising any further I decided to figure it out myself. Turns out that the Axxess web site has very clear instructions for how to install this unit. If you use "automatic mode" the "next track" button doesn't work. But if you program it in "manual mode"--very easy--ALL the buttons work fine. Problem solved, and I didn't even have to destroy my hardware button on the steering wheel by pushing real hard on the corner of it.
I should have learned this lesson long ago, but buying the unit from Amazon / Crutchfield whatever and installing it oneself is not that hard and a hell of a lot cheaper.