问数据网格中的rowCount不起作用

EN

<?xml version="1.0"?>

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:mx="library://ns.adobe.com/flex/mx"  
    xmlns:s="library://ns.adobe.com/flex/spark" xmlns= "*" >
    <fx:Script>
        <![CDATA[



        ]]>
    </fx:Script>

    <fx:Declarations>
        <s:ArrayList id="arrList1">
            <fx:Object name="Adobe Illustrator CS5" />
            <fx:Object name="Adobe AIR 2.0" />
            <fx:Object name="ColdFusion 9" />
            <fx:Object name="Dreamweaver CS5" />
            <fx:Object name="Flash Professional CS5" />
            <fx:Object name="Adobe Flash Player 10.1" />
            <fx:Object name="Fireworks CS5" />
            <fx:Object name="Flex 4.0" />
            <fx:Object name="Lightroom 2.0" />
            <fx:Object name="Photoshop CS5" />
        </s:ArrayList>
    </fx:Declarations>
    <s:Panel title="DataGrid Control Example" height="100%" width="100%">
        <s:Label width="100%" color="blue" text="Select a row in the DataGrid control."/>
        <mx:DataGrid id="dg" width="100%" height="100%" rowCount="5" dataProvider="{arrList1}">
            <mx:columns>
                <mx:DataGridColumn dataField="name" headerText="Name"/>
                <mx:DataGridColumn dataField="name" headerText="Phone"/>
                <mx:DataGridColumn dataField="name" headerText="Email"/>
                <mx:DataGridColumn  headerText="Select" >
                    <mx:itemRenderer>
                        <fx:Component>
                            <s:MXDataGridItemRenderer>
                                <s:DropDownList labelField="name">
                                    <s:dataProvider>
                                        <s:ArrayList id="arrList">
                                            <fx:Object name="Adobe Illustrator CS5" />
                                            <fx:Object name="Adobe AIR 2.0" />
                                            <fx:Object name="ColdFusion 9" />
                                            <fx:Object name="Dreamweaver CS5" />
                                            <fx:Object name="Flash Professional CS5" />
                                            <fx:Object name="Adobe Flash Player 10.1" />
                                            <fx:Object name="Fireworks CS5" />
                                            <fx:Object name="Flex 4.0" />
                                            <fx:Object name="Lightroom 2.0" />
                                            <fx:Object name="Photoshop CS5" />
                                        </s:ArrayList>
                                    </s:dataProvider>
                                </s:DropDownList >
                            </s:MXDataGridItemRenderer>
                        </fx:Component>
                    </mx:itemRenderer>



                </mx:DataGridColumn>
            </mx:columns>
        </mx:DataGrid>

    </s:Panel>
</s:Application>