Why no red dot if drawing in sub layers/Flash optimization?

[HHGG]

I read the red dot indicates the optimization for Flash (viewtopic.php?t=4726).
I saved my project of a walking man some days ago and wanted to continue now.

This is the project structure:

Code: Select all

Bones
  Head
  Body
  Leg_Top_Right
  (and so on)

All Vector sublayers of bones have the red dot.
So I was surprised my new vector layers didn't have them.

But now I checked what was the difference:

Until now I created a Vector layer, draw a form in it and
AFTERWARDS moved the Vector layer into the Bones layer.

But now AT FIRST I moved the Vector layer into the Bones layer
and then drawed a form in the Vector layer.

So why do I have to draw a form for a vector layer if it is a main layer
to optimize it for Flash?

Why isn't it possible to draw a Flash optimized form when the Vector is
a sub layer of bones?

[Update]
Now I have also the phenomenon that the red dots go away if I move
Vectors from the main layer to a sub layer of Bones.
And also if I move only the form in the same layer the red dot disappears.
I'm confused about the red dots.
And without the red dots the forms have a very low not usable qualitiy, so I have to fix it. But how?