_parent._name not showing up

programming flash
1

ok since no replyes to my last post ive added an example:
basicly in root i have this code:

var container_mc:MovieClip = this.createEmptyMovieClip(“container_mc”, this.getNextHighestDepth());
attachMovie(“button_mc”,“button_mcadded”,_root[container_mc]);

and the button_mc that has a btn called myb has this code

myb.onRelease = function (){
trace(this._name) //trace is correct
trace(_name) //trace is correct
trace(_parent._name) //traces a empty line not eaven undfined should trace container_mc
}