Problem with more keys pressed at once

This is not my code but it shows my exact problem

var upPressed:Boolean = false;

var downPressed:Boolean = false;

var leftPressed:Boolean = false;

var rightPressed:Boolean = false;

var WPressed:Boolean = false;

var SPressed:Boolean = false;

var APressed:Boolean = false;

var DPressed:Boolean = false;

box2.addEventListener(Event.ENTER_FRAME, fl_MoveInDirectionOfKey);

stage.addEventListener(KeyboardEvent.KEY_DOWN, fl_SetKeyPressed);

stage.addEventListener(KeyboardEvent.KEY_UP, fl_UnsetKeyPressed);

function fl_MoveInDirectionOfKey(event:Event)

{

    if (upPressed)

    {

        box2.y -= 5;

    }

    if (downPressed)

    {

        box2.y += 5;

    }

    if (leftPressed)

    {

        box2.x -= 5;

    }

    if (rightPressed)

    {

        box2.x += 5;

    }

    if (WPressed)

    {

        box1.y -= 5;

    }

    if (SPressed)

    {

        box1.y += 5;

    }

    if (APressed)

    {

        box1.x -= 5;

    }

    if (DPressed)

    {

        box1.x += 5;

    }

}

function fl_SetKeyPressed(event:KeyboardEvent):void

{

    switch (event.keyCode)

    {

        case Keyboard.UP:

        {

            upPressed = true;

            break;

        }

        case Keyboard.DOWN:

        {

            downPressed = true;

            break;

        }

        case Keyboard.LEFT:

        {

            leftPressed = true;

            break;

        }

        case Keyboard.RIGHT:

        {

            rightPressed = true;

            break;

        }

        case Keyboard.W:

        {

            WPressed = true;

            break;

        }

        case Keyboard.S:

        {

            SPressed = true;

            break;

        }

        case Keyboard.A:

        {

            APressed = true;

            break;

        }

        case Keyboard.D:

        {

            DPressed = true;

            break;

        }

    }

}

function fl_UnsetKeyPressed(event:KeyboardEvent):void

{

    switch (event.keyCode)

    {

        case Keyboard.UP:

        {

            upPressed = false;

            break;

        }

        case Keyboard.DOWN:

        {

            downPressed = false;

            break;

        }

        case Keyboard.LEFT:

        {

            leftPressed = false;

            break;

        }

        case Keyboard.RIGHT:

        {

            rightPressed = false;

            break;

        }

        case Keyboard.W:

        {

            WPressed = false;

            break;

        }

        case Keyboard.S:

        {

            SPressed = false;

            break;

        }

        case Keyboard.A:

        {

            APressed = false;

            break;

        }

        case Keyboard.D:

        {

            DPressed = false;

            break;

        }

    }

}

Why can't i make both boxes move towards the right corner at the same time?