@Niels Henriksen: I personally don't use Windows Vista to program in any way but some days ago I have seen something strange happening on Vista. I've realized a card game (based on the popular game "One". I suppose this would be its name in other countries. Here we call it "Uno") and on my Win XP SP3 works perfectly. The strange thing is that when I play with a friend of mine who has Windows Vista, game lights sometimes behave strangely.
What I'm suggesting is to try the same code on another operating system if you can. If you can't, then try to call MakeLight function directly, because of bugs afflicting Light classes.
This is why I NEVER program on Windows Vista.
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Anger leads to hate
Hate leads to suffering