What can I do to turn my screen brightness down when simple interface methods do not work?

I have installed Ubuntu 11.10 on my HP dv6 and so far the only problem i've had is that i can't turn down the screen brightness. I use the "hot key" the "short cut keys" I go to settings and make the slider all the way down to dim and nothing...my screen remains at the brightest setting....giving me a real bad battery life. Also, I'm accustomed to using low screen settings for reading/writing documents, emails, etc. I've tried using programs such as f.lux and Redshift but these attempts have been without success. I seem to find many others with the same problems. Anyone have any ideas?