stage.addEventListener(Event.ENTER_FRAME, enterFrameFunc);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownFunc);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpFunc);

var charSpeedVar:Number = 5;
var moveUpVar:Boolean = false;
var moveDownVar:Boolean = false;
var moveLeftVar:Boolean = false;
var moveRightVar:Boolean = false;

function keyDownFunc(event:KeyboardEvent):void{

if (event.keyCode == 39){
moveRightVar = true;
}
if (event.keyCode == 38){
moveUpVar = true;
}
if (event.keyCode == 37){
moveLeftVar = true;
}
if (event.keyCode == 40){
moveDownVar = true;
}

}

function keyUpFunc(e:KeyboardEvent):void{

if (event.keyCode == 39){
moveRightVar = false;
}
if (event.keyCode == 38){
moveUpVar = false;
}
if (event.keyCode == 37){
moveLeftVar = false;
}
if (event.keyCode == 40){
moveDownVar = false;
}

}

function enterFrameFunc(Event){
if(moveRightVar==true){
charMc.x += charSpeedVar;}
if(moveLeftVar==true){
charMc.x -= charSpeedVar;}
if(moveUpVar==true){
charMc.y -= charSpeedVar;}
if(moveDownVar==true){
charMc.y += charSpeedVar;}
}

The class or interface 'KeyboardEvent' could not be loaded.