I am unable to change the brightness of my desktop screen using this path. System settings{top right corner of the screen)>Under Personal Brightness & lock.No option to change brightness is available here.In Ubuntu 11.04 Shift+ +/- key was used to change brightness,the same doesn't work in 12.04.
Also under System settings{top right corner of the screen)>Under Hardware Displays,my monitor is recognized as a Laptop despite me using a desktop!