Professional :: Simple Mask Not Working In Flash CS4?

I am creating a very simple mask using motion tweening. I created some text on a layer and made it a masked layer. Then I created a mask layer which consists of a circle that will span across the text. When I play the movie the circle does not show up at all in the frames the mask layer spans (it's purple on a black background) and the circle does not move across the text like I told it to with the motion tweening. I don't know why it's not working. For some reason the circle isn't showing on the stage at all and it's not moving across the text. I don't know if I have it set up wrong on the timeline or what. Here's the steps I followed to create the mask:

1.insert a new layer in which I named it mask and click frame 1 on this layer

2. select the oval tools on the tools panel and set the stroke to none

3. set the fill color to purple

4. draw a circle and click the selection tool and drag a marquee around the circle to select it.

5. click insert on the menu bar, click motion tween then click ok in dialog box about converting it to a symbol to be tweened

6. click the last frame in the mask layer and drag the circle to the end of the line of text

7.click mask on the timeline to select the mask layer, click modify on the menu bar, point to timeline then click layer properties

8. verify the show check box is selected in the name section, click the lock check box to select it, click the mask option button in he type section, then click ok.

9. play the movie in which the circle object covers the text on the masked layer as it moves across the stage.