Can you be more specific? At what point does it say "no results found?" How exactly are you tagging?
For example, I'm just writing "clseale" (clseale) in my note, it doesn't verify or look anything up when I do that, and then I'll hit "Post quick reply." If you type "@_y4m" (without the quotes or dash - I'm just putting that there so you can see it) and save, what happens?
ETA: Ok, nevermind. That wasn't working before either. It was just showing the @ sign and the name, but now I guess it's just the tagging button that doesn't work. I can work around that though. Thanks!