@Baardvark You are right, moving it to Proc doesn't change anything. I thought it was one of those functions called only in Proc commands.
@JecklynHyde
For your error, it's simply that the function FadeToBlack() takes REAL seconds as second argument, which means a number with a decimal. The error reported by Osiris was complaining that the definition was changed. That means that one of your variable is the wrong type.
FadeToBlack(CHARACTER_Player1,500.0,1);
For scripting references, these tutorials helped me a lot!
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=521809#Post521809