OOp help

programming flash
1

Hiya… Im trying out some basic OOP… and cannot understand where I am going wrong. It works within the timeline - but when I transfer to Packages It doesnt work where concerning the property of the bitmap.
I have a ‘MyClip’ instance in the library.
here is my bask Document Class package::

package {
    import flash.display.*;
    import flash.events.*;
    
    public class MyMain extends MovieClip
    {
        public var pic:MyClip = new MyClip();
        
        public function MyMain():void
        {    
            Render();
        }    
        
         public function Render()
        {    
            this['bmp'] = new     BitmapData(stage.stageWidth,stage.stageHeight,true,0x000000);
            this['bmp'].draw( pic );                
            this['item'] = new Bitmap( this['bmp'] );
             
            this.addChild( this['item'] );    
        }
    }
}

the this[‘bmp’] is to be used with this[‘bmp’+i] to make multiple instances within a loop … and Ive seen that method used before. IF I take out the this[‘bmp’] and replace with var bmp = new… etc - then it works. Hmm
can anyone guide me home?
Thanks!