Making a scribled line with an animation

I want to make a animated scribled line (like something you draw with the paintbrush)
The viewer would get the idea that the scribled line is being drawn as he looks at it.
i have been working with flash 4 and got a little ball to follow a scribled “motion tween” line but how do i fill up the line?

I hope you can help me with this,
Silvester
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