Flex AdvancedDataGrid的使用，谁能告诉我呀？

注：第一列是带Checkbox的Tree。

还有问题请教各位：

labelField是元素对象的属性是显示不了（carInfo.car_name），好像只可显示同级的属性怎么解决？希望各位能帮助我，Thanks!

<mx:AdvancedDataGrid id="adg" width="100%" height="100%" dataProvider="{instance.cars}"
variableRowHeight="true" wordWrap="true" verticalGridLineColor="0x339900" headerColors="[0x339900,0xFFEBCD]" horizontalGridLineColor="0x8B4513">
<mx:columns>
<mx:AdvancedDataGridColumn headerText="vehicle name" dataField="carInfo.car_name"/>
<mx:AdvancedDataGridColumn headerText="terminal key" dataField="carInfo.terminal_key" />
<mx:AdvancedDataGridColumn headerText="sim code" dataField="carInfo.sim_code"/>
</mx:columns>
</mx:AdvancedDataGrid>

/*****vo.Car****/

[Bindable]

public class Car
{
private var _term:BaseTerminal;
private var _imageName:String;
private var _icon:Icon;
private var _carInfo:CarInfo;

...............

}

[Bindable]
[RemoteClass(alias="vo.Car")]
public class CarInfo
{
public var car_name:String;
public var car_id:String;
public var group_name:String;
public var speed:int;
public var terminal_key:String;
public var sim_code:String;
public var fuel_min:int;
public var fuel_max:int;
public var fuel_size:int;

...........

}