I'm trying to create a basic shape tween consisting of a line drawing itself
starting from a dot. I draw the dot in frame one then the full line in frame
15 as per the instructions. I create a shape tween. The tween arrow appears
normallly on the green shaded transition frames BUT, no tween. The drawn
elements were not made into symbols as advised in the instructions.

So what's missing here?

MX 2004 Pro / Mac

Update:

When clicking on keyframe 15 where the second line is there's a warning icon
stating "shape tween will not occur on layers with symbols or grouped objects".
Problem is there are no symbols ot grouped objects on the layer just two drawn
elements. in two different key frames on the same layer....

I initially applied the tween when a ramdom frame within the transition was
selected. Selecting either end keyframes showed no tweening info so i applied
the tweening command when each end keyframe was selected. That's when I saw the
warning button (only on the end frame).

Update 2:

Creating a fresh document and starting over with a similar tween Things Work!
BUT, strange behavior going on. I created a line then a new keyframe, then
*scale* the line in the second keyframe, then applied shape tween. it Works.
The I scale the line again for adjustment. Tween fails. Line element disappears
during transition. WTF??

Another strange thing, After scaling the line (down to a dot) then deselecting
the element, it actually gets deleted. (disappears from the stage and
timeline). What is going on?.....

MX 2004 Pro / Mac OSX 10.2.6

You can tween between a very very very short line and a long line. You could put a dot into the frame before the tween starts.