The sun lighting probably isn't 'working'-- the skybox is just always fullbright. Can you post the worldspawn parameters you're using?
I am using:
"classname" - "worldspawn"
"sky" - "pbsky4"
"_sun_light" - "500"
"_sun_angle" - "75 -30"
"_sun_diffuse" - "200"
"_sun_ambient" -"30"
of course, i am only testing out lights, so i just chose some random numbers that i found on the fourms to test.
Also, did you add a light value of 150 to the sky sufraces?
I dont know how to do that yet.
EDIt: I got it working. Thanks