Adjusting line _width with AS changes _height too??

I have a horizontal line that is in a movie clip. To adjust the width of the line when I click a button I use

Code:

---

btn.onPress = function(){
        line._width += 20;
}

---

This does change the width, but the line gets thicker (height is increasing) as the width increases. Why is this happening, and how can I keep it from happening? I want only the length of the line to change, not its thickness...

Thanks for your help!

Ok, solved it. Set the "scale" property of the line to "none", and it works >.<