Not sure, I couldn't get it to work either. I just gave up and figured if I could give my character max stats, I could easily take or barter anything in the game I wanted. The only annoying thing I've found is that you can't drag more than 999 gold at a time to your barter bit.
Anyway, yeah, I didn't look into it, but I experienced the same issue, it's my opinion that it maybe doesn't work by default or you have to have a 3rd party patch installed.