You didn't tell us if you had or not, so I had to assume that it was something you'd just tried and cover all bases. It's easiest to start with the easy things
Do all of the other features of Plus! function correctly?
Do you have any Messenger Plus! Live Skins installed?
We don't know what your exact problem is, this hasn't been encountered before to my knowledge, hence we're asking you questions to try to figure out what's causing it and how to solve it