If I try from a user account also, then also its not working.
There is no error when I select the 'Lock session' from start menu. Nothing happens. When I had first installed CentOS, it was working, but over the days, I have been fiddling around with a lot of settings. Thus it seems to have broken.
Originally Posted by oskar
Are you logged into x as root?
Don't do that.
If you're logged in as user and you're trying to lock the screen as root - that won't work either. Try again as user from the command line. Is there any error message when you just use start-'lock screen'