[need help]cant get senoculars duplicatemovieclip alternative to work

programming flash
1

I was checking out this tip by senocular
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I dont know what am I doing wrong, If possible somebody please guide me
mycode

package {
    
    import flash.display.DisplayObject;
    import flash.geom.Rectangle;
    
    /**
     * duplicateDisplayObject
     * creates a duplicate of the DisplayObject passed.
     * similar to duplicateMovieClip in AVM1
     * @param target the display object to duplicate
     * @param autoAdd if true, adds the duplicate to the display list
     * in which target was located
     * @return a duplicate instance of target
     */
    public function duplicateDisplayObject(target:DisplayObject, autoAdd:Boolean = false):DisplayObject {
        // create duplicate
        var targetClass:Class = Object(target).constructor;
        var duplicate:DisplayObject = new targetClass();
        trace(targetClass)
        // duplicate properties
        duplicate.transform = target.transform;
        duplicate.filters = target.filters;
        duplicate.cacheAsBitmap = target.cacheAsBitmap;
        duplicate.opaqueBackground = target.opaqueBackground;
        if (target.scale9Grid) {
            var rect:Rectangle = target.scale9Grid;
            // WAS Flash 9 bug where returned scale9Grid is 20x larger than assigned
            // rect.x /= 20, rect.y /= 20, rect.width /= 20, rect.height /= 20;
            duplicate.scale9Grid = rect;
        }
        
        // add to target parent's display list
        // if autoAdd was provided as true
        if (autoAdd && target.parent) {
            target.parent.addChild(duplicate);
        }
        return duplicate;
    }
}

import duplicateDisplayObject;


var newMc = duplicateDisplayObject(oldS, true);//***oldS*** is an on stage mc instance
newMc.x = 300;
newMc.y = 200;

trace (newMc.x);

the trace function works, but not able tosee the newMc on stage
someone please explain,

thanks