Help with shape tween

This is a newbie question, but i havent found any answers to it elsewere, so i’m posting here.

I’m trying to scale an object i drew in flash mx 2004 (just lines and fills) to twice its size in 30 frames.

I’m using a shape tween.
This works for really simple objects (circle, polygon) but the instant i have more lines or fills** the object falls apart during tween** and than comes back together in the desired scale at the and of 30 frames.

What am i doing wrong?

thanks