Errors using document class and addChild

1

I am curently learning as3, and am trying to do a tutorial from the adobe site. Unfortunately the sample file on the site doesn’t seem to be the right one. and I keep getting three errors when I run it.

1180: Call to a possibly undefined method addFrameScript.
1180: Call to a possibly undefined method addChild.
5000: The class ‘Snowflake’ must subclass ‘flash.display.MovieClip’ since it is linked to a library symbol of that type.

What the tutorial is supposed to make is a snow effect. I am boggled by the 5000 error because I am not linking to any library symbols. There is nothing in the fla except a small line of code on frame 1 of the timeline.

snow.fla:


for(var i:uint; i<800; i++) {
	var SNOWFLAKE:Snowflake = new Snowflake();
	addChild(SNOWFLAKE);
}

I have the Document Class set as Snowflake in the properties bar.

Snowflake.as looks like this:


package {
    import flash.display.Shape;
    import flash.events.Event;
    import flash.filters.BlurFilter;

    public class Snowflake extends Shape {
        private var stageWidth:int = 550;
        private var stageHeight:int = 450;
        private var highestDropSpeed:uint = 16;
        private var dropSpeed:int = Math.round(Math.random() * Math.random() * highestDropSpeed);
        private var incrementer:int = Math.round(Math.random() * 100);
        private var shades:Array = [ 0xFFFFFF, 0xCCCCCC, 0x999999, 0x666666 ];
        private var windSpeed:int = 2;

        public function Snowflake() {
            graphics.beginFill(shades[ Math.ceil(Math.random() * shades.length) ]);
            graphics.drawCircle(0,0,4);
            graphics.endFill();

            filters = [ new BlurFilter(1,dropSpeed,1) ];
            addEventListener(Event.ENTER_FRAME,update); 
            reset();
        }
      
        private function reset():void {
            y = Math.random() * stageHeight * -1;
            x = Math.random() * stageWidth - (windSpeed*100);
            scaleX = scaleY = 0.25 + (Math.random() * Math.random() * 0.75);
        }

        private function update(e:Event):void {
            y += dropSpeed;
            x += windSpeed + Math.sin(incrementer/10) * (1/(dropSpeed/3));
            
            if (y > stageHeight) {
                reset();
            }

            incrementer++;
        }
    }
}

Any help would be great!