Bitmap disappear after setChildIndex

1

I have a bitmap inside a Movieclip. So, when I swap the parent, the bitmap disappears… This is my setup:

ScreenMC Children:
0. name:instance178 type:object [object Sprite]

  1. name:instance176     type:object    [object MovieClip]

  2. name:instance16     type:object    [object Bitmap]

After this:

_currentScreen = _Container.getChildByName(some_string) as ScreenMC;
_Container.setChildIndex(_currentScreen,Number(_Container.numChildren - 1));

Than, I load another ScreenMC object, and when I swap back the first ScreenMC, I get this:

ScreenMC Children:
0. name:instance178 type:object [object Sprite]

  1. name:instance176     type:object    [object MovieClip]

On ScreenMC, I have this:

_bgBitmap = new Bitmap();
_bgBitmap = Main.bgsDictionary[“bg1.jpg”] as Bitmap; // grab Bitmap object from a dictionary
_bgHolderMc.addChild(_bgBitmap);

Why?

Thanks