'Special' keys may need to be caught and manually linked to alsa/brightness. I'm on an Acer c720 with similar challenge.
Try using xev to catch/identify key press/release codes. Then use actkbd (or something like that) to call your own volume/brightne...
Try using xev to catch/identify key press/release codes. Then use actkbd (or something like that) to call your own volume/brightne...
