Ok, your wrong. I want a light_Enviorment. I want to make my map semi dark. So, at this time I have got the Light_Enviorment working. However, event when I change the brightness and make it say "2" it still is too bright. I have looked in to tutorials and such, but everything I am trying is not particularly working.
Check Hammer's Entity Report and make sure you only have one light_environment.
Or maybe it is working already: with a color/brightness of 255 255 255 2
you will still be able to see pretty clearly. You can go as low as 1 1 1 1
so keep lowering it until you like it.