Scroller from v5 to MX won't work!

Here is the problem:

I created a movie on Flash 5. Now I’m trying to fix up the movie by editing it on Flash MX. I’m trying to add a scroll bar but the bar won’t auto-scale to fit the Text Box. I tried the same thing on a newly created MX document and it worked perfectly. But when I try using the movie created in Flash 5 it won’t work. By the way, the movie is now saved on the MX format but it still won’t work. Any suggestions? Thank you.