Actionscript 3 movieclip中的Actionscript 3按钮

TypeError:Error#1010:术语未定义且没有属性。在 mygame_佛罗里达州：：主要时间线/选项BTN（）

或

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它仍然有以下错误类型error:error#1010:术语未定义且没有属性。在mygame_佛罗里达州：：主时间线/选项BTN（）

function OPTIONbtn(e:MouseEvent):void 
{
    trace("play");
    var ClickSound:click_sound = new click_sound();  //attach sounds 
    var myChannel:SoundChannel = ClickSound.play();
    var optionBOX:MovieClip = new option_box();  //attach movieclip
    addChild(optionBOX);
    optionBOX.x = 480;
    optionBOX.y = 300;

    optionBOX.ok_btn.addEventListener(MouseEvent.CLICK, OKbtn);
    function OKbtn(e:MouseEvent):void 
    {
        trace("my ok button");
    }
}

function OPTIONbtn(e:MouseEvent):void 
{
    ///...
    optionBOX.ok_btn.addEventListener(MouseEvent.CLICK, OKbtn);
}

function OKbtn(e:MouseEvent):void 
{
    trace("my ok button");
}

function OPTIONbtn(e:MouseEvent):void 
{
    ///...
    optionBOX.ok_btn.addEventListener(MouseEvent.CLICK, function OKbtn(e:MouseEvent):void 
    {
        trace("my ok button");
    });
}