Problem with shape tween

Hi Everyone,

the picture below shows a problem with a shape tween
thatI’m trying to avoid…

a box for eg. startin at H and L 2 the next keyframe it’s H is 2 and L 200 let’s say. Now the tween itself looks weird… like this…

why is that…that’s so weired…

I appreciate your help guys,

thanks,

mucho