Why isn't Gamma enabled?

Night time in SL is usually so dark that I can't see anything on the default SL settings, so I always bumped up my "Nighttime Brightness" settings in the old viewer. The new viewer does have a gamma option (Edit > Preferences, check Custom, Hardware Options, Gamma), but it's grayed-out for me, and now I'm stuck with having to dork with my lighting settings if I ever go someplace at night. Any idea why I wouldn't be able to change this option?

Running an Intel/Vista notebook with NViDIA GeForce Go 7600, 256MB video memory. Windlight works really well on this system, except for some weirdness with megaprims (very large ones go transparent).

world / enviroment settings / advanced sky / lightning / scene gamma,

^Only way, and no its not very good at all, wich is really annoying since set nighttime gamma was usefull , course thats gone and been asked for give me it back? no reply, or youll get "post it on jira" so we can forget about it probably hurr.

They still need a option to bind presets to shortcuits -.-, and why doesnt SL client have a shortcuit to "set nighttime"? but, Middays , Sunset , have one.

Ouch, that really sucks. I've actually been working with windlight for some time, and I can't believe I never noticed this before.

Uncheck 'Atmospheric Shaders', change the gamma setting and recheck.

Nice, thank you! (Yep, user-friendly-er than ever!!!)