I have gone through valve's tutorials for making a sky (cubemap) about 20 times, and it doesn't work. What doesn't work is inputing 'buildsubemaps' into console since after that input... the game crashes with an error report about 'datacache.dll'

... if anyone has any easier way of creating a realistic sky - plz reply and preferably (if you can), show me a visual tutorial (a video) of how to make a proper sky so that I can add appropriate lighting.
Thx a bunch if you can offer me a solution
AVZ