backlight keyboard isnt working

Hi,

The keyboard backlight of my new Laptop Inspiron 15 5558 ( bought on January)  is not working, i didnt even know it got this feature until i saw one of my friends who bought the same laptop and it got backlight keyboard, i tried using the F10 button but nothing happens when i press it and there is no backlight icon in the windows mobility center so i can switch it on , please help !