I too was mislead by the manual stating that it had a backlight. One of the reasons I bought it. In the dark it's impossible to see the keys. I too found after numerous attempts to get an answer out of Samsung that noone could tell me why the manual had the KB backlight as a feature .
I didn't think mine had a backlight on the keyboard either but it does. Press the FN key and F9 and it should turn on. There are 3 separate setting for dim, medium, and bright. And the 4th press turns backlight off.