Can't manage it!

1

I get to make a fine movie in Flash the action script is good everything goes smooth and fine and amazingly WORKS. But when I try to change something in it for example like a button or something, it no longer works. Even if I changed the button’s name in the scrip it still doesn’t work. Plssssss help me!! What am I doing wrong? Cause if I make the movie again from the beginning with the additional changes it works, but if I want to introduce them…it doesn’t :(((((((((