getBounds doesn't works, how to?

Hello !
This is my problem, I have a MC, it contains many others MCx, and I need to test if these MCx are inside a zone, even when I rotate my MC, I’m doing this with getbounds(), and it works great but only when my MCx are in the DisplayObjectContainer list, if I remove them, then getbounds() doesn’t work, at really it shows my original bounds (not my “rotated” bounds…).
I think this is because the MCx objects are not inheriting the rotationX property anymore (because MC.getbounds() works good even when I remove MC from the stage, I think this is because MC.rotationX is directly modified…).
So, my question is, how can I implement my own getbounds()? I need a way to know how is made the projection in flash.
I found this in the help (z property from DisplayObject)
The X and Y position in the window:
X = xcameraFocalLength/cameraRelativeZPosition
Y = y
cameraFocalLength/cameraRelativeZPosition

But I don’t know how to obtain these two values (cameraFocalLength and cameraRelativeZPosition)

Please I need help with this.
THANKS !!!
enrique.
PS: sorry for my bad english :frowning:

PS2: the code looks like this:
MC.rotationX = -30;
MC.getBounds(this); //works great
MC.mc1.getBounds(this); //works great

MC.removeChild(MC.mc1);
MC.getBounds(this); //works great
MC.mc1.getBounds(this); //doesn’t work, it shows the original ("planar, not rotated) bounds

removeChild(MC);
MC.getBounds(this); //works, not so great, but at least the height and width are correct