Error #2136: The SWF file

Question

I am trying to learn how to use classes.The book i am using gave me this example.
In Vechile.as
package{
            import flash.display.MovieClip;
            import flash.events.Event;
            public class Vehicle extends MovieClip{
                        public var _gasMileage:Number;
                        public var _fuelAvailable:Number;
                        public var _milesTraveled:Number =0;
                        public var _go:Boolean;
                        public function Vehicle(mpg:Number=21, fuel:Number=18.5){
                                    _gasMileage=mpg;
                                    _fuelAvailable = fuel;
                                    this.addEventListener(Event.ENTER_FRAME, onLoop, false,
                                    0, true);
            public function onLoop (evt:Event):void{
                        if (_go){
                                    _fuelAvailable--;
                                    _milesTraveled+=_gasMileage;
                                    if (_fuelAvailable < 1){
                                                this.removeEventListener(Event.ENTER_FRAME,
                                                onLoop);
                                    trace(this, _milesTraveled,_fuelAvailable);
                                    this.x=_milesTraveled;
            public function go():void{
                        _go = true;
In the main.fla
In frame 1
var vehicle:Vehicle = new Vehicle(21,18.5);
addChild(vehicle);
vehicle.go();
when I compile it gives an output error.
Error #2136: The SWF file file:///C|/Users/Ravenwind/Documents/Main.swf contains invalid data.
                at Vehicle/frame1()
I am stumped

Answer 1

" I then assign Vehicle to document class box in the property box" Do not assign the Vehicle as the document class... remove it from there. 
In the main file, if you didn't already create one, create a movieclip symbol (just draw a shape in it for now).  Right click the symbol in the library and select the Linkage option.   In the interface that appears, select the option to Export for Actionscript, and assign it the Class name "Vehicle" in the field labeled "Class"
Make sure you save the Vehicle.as file after you put the code into it and have that file in the same folder as your Main.fla file.
If you do the things I just described you should see an instance of the movieclip moving across the stage when you run the file.