Oh, what is wrong with it then? Do you happen to have a working one?

I did some calculations and the vectors in the file do seem to be normalized. As I sayd I'm not sure about the order of sides.

Alexander, I dont think its wrong.. it look like the same one i used before..

Like this: http://www.cescg.org/CESCG-2002/GSchroecker/img33.png

The order should be -x, +z, +x, -z, -y, +y - with the orientation shown in this picture.

To test your cubemap, just place a sky-box in your level and assign it - it's as easy as that to check if it alligns correctly.

If it really works like a sky box then it must be right, behind, left, front, down and up. At least this is the order when I create sky cubes for Gamestudio.