AddChild in AS3 error

Question

In Flash CS5 I am trying to load an image from a  class and I am getting
Call to a possibly undefined method addChild.  In the  class file
Not sure how to fix this as I have a sprite class and believe I have done everthing correct.
The image is in the same folder as the .fla and .as file
//class
package  {
       import flash.display.*;
     public class ClassImg extends Sprite{
          import flash.display.Bitmap;
          import flash.display.Loader;
          import flash.display.Sprite;
          import flash.events.Event;
          import flash.net.URLRequest;
          import flash.text.*;
          public function ClassImg()     {
               var loader:Loader = new Loader;
          loader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded);
          loader.load(new URLRequest("ladybug.png"));
          private function imageLoaded(event:Event):void
               var image:Bitmap = new Bitmap(event.target.content.bitmapData);
               image.x=10;
               image.y=10;
               this.addChild(image); //error is here and I tried just addchild
//in .fla
var li:ClassImg= new ClassImg();
addChild(li);

Answer 1

yes it works with the import statements in the other area. I must say it took over a day for someone to find the answer to this so well done again.
q1)Now I am new to this so I believe I need to display an image in a sprite or movie clip container and by extending the class with sprite I am doing this?
q2) Say I want to make a call to a method in the class which moves the image position to say 200,200.
How do I set the image to a variable and simply move it?
The issue is I need an event to tell me the bitmap has loaded so in the fla file I can then be able to move the image.
PS I dont get that error and I need the sprite and not movie clip. I am using flash CS5 trial. I would like to know why you get this problem