How can I control movieclip attached AS3?

programming flash
1

I have one movieclip in library.

linkage = mcPai. This movie has into here another MovieClip instance = mcFilho.

Flash as2 I can do this:

container.attachMovie(“mcPai”, “instance1”, this.getNextHighestDepth());
instance1.mcFilho._x = 100;

But in AS3 has a error.

container.addChild(new mcPai());
container.mcFilho.x = 100;

TypeError: Error #1010: A term is undefined and has no properties.
at attach_fla::MainTimeline/frame1()

I need some help.
Thanks.