Setting properties of objects found using getChildByName

programming flash
1

Hi, assistance appreciated.

I am attempting to set the propreties of a navigation button (movie clip) that has been built dynamically. The button contains a text field that I want to format and a movie clip that I want to adjust the alpha. I find the object using getChildByName(), however do not seem to be able to set the properties using the code below.

These lines throw errors:
navObj.mainNav_txt.setTextFormat(buttonFormat);
navObj.smallSun_mc.alpha = 1;

Any help appreciated

Patrick

 
private function setNavState(e:Event):void {
   if(xml) {    
    var navObj:DisplayObject = getChildByName(onNav);
    var buttonFormat:TextFormat = new TextFormat();
    buttonFormat.bold = true;
    navObj.mainNav_txt.setTextFormat(buttonFormat);
    navObj.smallSun_mc.alpha = 1;
    stage.removeEventListener(Event.ENTER_FRAME, setNavState);
   }
  }