用FLASH編程序，遇到“1120: 訪問的屬性 hs1 未定義。”，請問是什麽原因，我在下面將這段代碼附上

fk1_mc.addEventListener(MouseEvent.MOUSE_DOWN,zt1fk1);

function zt1fk1(event:MouseEvent)

{

fk1_mc.startDrag();

this.stage.addEventListener(KeyboardEvent.KEY_DOWN,hs1);

}

function hs1(event:KeyboardEvent)

{

switch (event.keyCode)

{

case 65 :

fk1_mc.rotation-=3;

break;

case 68 :

fk1_mc.rotation+=3;

break;

case 87 :

fk1_mc.scaleX+=0.2;

fk1_mc.scaleY+=0.2;

break;

case 83 :

fk1_mc.scaleX-=0.2;

fk1_mc.scaleY-=0.2;

break;

}

}

fk1_mc.addEventListener(MouseEvent.MOUSE_UP,zt2fk1);

function zt2fk1(event:MouseEvent)

{

fk1_mc.stopDrag();

this.stage.removeEventListener(KeyboardEvent.KEY_DOWN,hs1);

}

fk1_mc.buttonMode=true;