Scroll bar troubles

hello there.
ive been trying to make a scroll bar for about a week now, and this site is the only one ive found that gives you a decent tutorial on how to do it. so good work kirupa.
i was following this tutorial

http://www.kirupa.com/developer/flash8/scrollbar.htm

which was very good. it showed me how to make one and then i used this to go on and make my own custom one, BUT, and there is a but, for some reason when i go to play the movie, the scroll bar comes up as being about halfway off at the top of the screen, and when i click on the scroll bar to drag it down, it jumps to about half its own width to the left, and scrolls up and down there, rather than along the track.

can anyone help me? i havent modified the code at all, and i wonder if this may be the case, as my project is a different size, and i have also trimmed down the width of the scroll bar.
any help would be greatly appreciated, as this is driving me mad being so close to finished!