Anybody know why my codes not working?

1

Im not entirely sure where the problem is coming from, however I keep getting error msgs when I try to export my game saying:

1120: Access of undefined property onKeyPressed.
1120: Access of undefined property onKeyReleased.
1120: Access of undefined property frameLoop.

var instructions:InstructionsPage;
var gameScreen:GameScreen;
var endGameScreen:EndGameScreen;
public var sc:Scuba;
public var vx:int;
public var vy:int;
public var leftPressed:Boolean;
public var rightPressed:Boolean;
public var upPressed:Boolean;
public var downPressed:Boolean;
public var sharkArray:Array;
public var numberOfSharks:int;

    public function Main(){
        instructions = new InstructionsPage();
        gameScreen = new GameScreen();
        endGameScreen = new EndGameScreen();
        
        stage.addEventListener(KeyboardEvent.KEY_DOWN,   onKeyPressed);
        stage.addEventListener(KeyboardEvent.KEY_UP, onKeyReleased);
        addEventListener(Event.ENTER_FRAME,frameLoop);