I have tried to active post release ATI AMD, but it seem don't work, anyone you know how to do this? please thanks http://imageshack.us/photo/my-images/854/screenshotfrom201206141.png/
Try doing this from terminal:
If that doesn't worked try doing these steps
Then if there aren't errors try rebooting.
P.S. If you prefeer the packages are also in Ubuntu Software Center so you can install them from it.