TourdeFLEX的一个例子在我机器里面报错!!

XML code

<?xml version="1.0"?><!-- Simple example to demonstrate the ComboBox control. --><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" backgroundGradientColors="[0x000000,0x323232]" viewSourceURL="srcview/index.html">    <mx:Script>        <![CDATA[            import mx.collections.ArrayCollection;            [Bindable]            public var cards:ArrayCollection = new ArrayCollection(                [ {label:"Visa", data:1},                   {label:"MasterCard", data:2},                   {label:"American Express", data:3} ]);                    private function closeHandler(event:Event):void {                               myLabel.text = "You selected: " +  ComboBox(event.target).selectedItem.label;                myData.text = "Data: " +  ComboBox(event.target).selectedItem.data;            }             ]]>    </mx:Script>    <mx:Panel title="ComboBox Control Example"         height="75%" width="75%" layout="horizontal"        paddingTop="10" paddingBottom="10" paddingLeft="10" paddingRight="10"        color="0xffffff" borderAlpha="0.15">        <mx:ComboBox dataProvider="{cards}" width="150" color="0x000000"            close="closeHandler(event);"/>        <mx:VBox width="250" color="0x000000">            <mx:Text  width="200" color="blue" text="Select a type of credit card."/>            <mx:Label id="myLabel" text="You selected:"/>            <mx:Label id="myData" text="Data:"/>        </mx:VBox>             </mx:Panel>    </mx:Application>

我拷里面的代码，Flex SDK 是3.2，closeHandler函数中的两句话都有问题，1119:访问可能未定义的属性 selectedItem(通过static类型ComboBox引用).我同事机器里面好好的，为啥在我机器里面有问题？？

[解决办法]
ComboBox没导入啊，上面加上import mx.controls.ComboBox;
[解决办法]
把错误贴出来看看