[flexcoders] checkbox in datagrid

[li_rang]

Hi, All, 

I have a strang problem in datagrid, the last column in my datagrid 
is based on checkbox, but the when i click the checkbox, it turned to 
textinput again. Here are my code:
<mx:DataGrid  id="dg_detail" dataProvider="{detail}" editable="true" >
   <mx:columns>
                                        
        <mx:DataGridColumn headerText="Name" dataField="name" 
editable="false" />
                                        
        <mx:DataGridColumn headerText="Instock" dataField="instock" 
editable="false"/>
                                                
                                        
        <mx:DataGridColumn headerText="Add to List" 
dataField="select" itemRenderer="mx.controls.CheckBox" 
editable="true"/>
    </mx:columns>
</mx:DataGrid>

any help will be appreciated. thanks