I press FN key and try to change brightness level. Brightness value go up and down, but brightness still the same on 100%.
have you done a full system update?:
Try to install “samsung-tools for trusty(14.04)”, reboot, and then install “samsung-backlight for quantal(12.10)”(that’s the newer version available) and reboot. Download those 2 files [here]
In my case, it worked fine on Samsung R530, Ubuntu MATE 14.04