ActionScript 3.0 :: Getting Error 1009 When Adding Preloader To Flash Movie

I'm trying to add a preloader to my flash movie so the user doesn't have to wait for additional frames to load while they are navigating. When I try to shift my current frames over by 2 frames to make room for the preloader I get this error:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at APIVisionDigitalRecall_fla::MainTimeline/frame3()[APIVisionDigitalRecall_fla.MainTimeline::frame3:20]
at flash.display::Sprite/constructChildren()
at flash.display::Sprite()
at flash.display::MovieClip()
at navBar()

Everything works fine before I shift the frames by 2, so I don't understand why I'm getting a complier error abut an object not existing. What to do to add a pre-loader to my existing movie without moving everything over by two frames?

I was planning on putting this code on frame 1:
ActionScript Code:
var kbtotal:Number=stage.loaderInfo.bytesTotal/1024;
var kbloaded:Number=stage.loaderInfo.bytesLoaded/1024;
var percent:Number= Math.round(kbloaded/kbtotal*100)
loader.gotoAndStop(Math.floor((precent/100)*100));
loader.loadingStatus.text=Math.round(kbloaded) + " lb / " + Math.round(kbtotal) + "kb";

This code on frame 2:
ActionScript Code:
if (kbloaded == kbtotal){
gotoAndPlay("Main");
} else{
gotoAndPlay("Load");
}