Mavericks Hot Corners does not work I have set up a hot corner for my screensaver on system preferences but it does not activate when i move my cursor to the appropriate corner of the screen.
Usually this is a temporary glitch that a restart fixes. If you have this failing after that - you can test a new user account.

If that works, then your preference file needs to be cleared. See this post for details: Hot Corners for Mission Control stop working