Correct way to implement cache as bitmap to deeply nested movieclips? help!

Question

I've been really stuck at this problem for a number of days and cant find any help online as to where im going wrong.
1119: Access of possibly undefined property CloudsNAnim through a reference with static type Class.
the setup as of now, there are 4 movieclips i want to cacheasbitmap. two copies of a vector movieclip called CloudS2 and two copies of one called CloudS4
those are in a movieclip holding them called CloudsNear and another movieclip holding that which holds an animation of the CloudsNear movieclip moving past the screen in a loop which is called CloudsNAnim
and that is inside the main level which is added to the stage called PlaneLevel
where do i place the cacheasbitmap lines in my code to load them into memory before I load the main movieclips
package
      // all my imports etc //
    public class MightyMend extends MovieClip
        public function MightyMend()
            // constructor code
            addChild(PLoading);                      //this loads my loading screen png to the stage
            stage.addEventListener(Event.ENTER_FRAME, loading); //reoccuring event listener happens as often as is set by FPS
            PlaneLevel.CloudsNAnim.CloudsNear.CloudS2.cacheAsBitmap = true;    
            PlaneLevel.CloudsNAnim.CloudsNear.CloudS4.cacheAsBitmap = true;     //these lines dont work
        private var PLoading:Bitmap = new Bitmap (new PlaneLoading());       
        private var PLevel:PlaneLevel = new PlaneLevel();   
        public function loading(e:Event):void //
            var total:Number = this.stage.loaderInfo.bytesTotal;
            var loaded:Number = this.stage.loaderInfo.bytesLoaded;
            var percent:Number = loaded/total * 100;
            trace (percent);
            if (total == loaded) //checks if all bytes for all movieclips have been loaded
                stage.removeEventListener(Event.ENTER_FRAME, loading);
                onComplete();
                 //the rest of the code staes that when oncomplete it will remove the loading screen and add the plevel to the stage etc..

Answer 1

The movieclip is called Plane_Level but i had linked it to actionscript as a class nameed PlaneLevel
im not sure if that makes a difference but when iadded that declaration
the line :
private var PLevel:PlaneLevel = new PlaneLevel();
now gives an error
1046: Type was not found or was not a compile-time constant: PlaneLevel.
1180: Call to a possibly undefined method PlaneLevel.