Flash Question

[Cap'n Crunch]

I have been working on my Flash cartoon for a little bit, and then I came to stop when I had a problem. Nothing on Flashkit helped, and I think there are some people on this board that have Flash, so here my problem. I have movie clips of characters walking, and I know how to make them move across the screen using motion tweening, but when I try to make more than one charcter move across the screen at once, it makes it bigger in the end of the tweening. Does anyone have a solution to my problem?