Checkbox not checked in dropdown itemrendere flex

I have DropDownlist which have Itemrenderer like following:

<s:DropDownList dataProvider="{testList}" labelField="test" 
                        itemRenderer="DropDownSelectRenderer"/>

ItemRenderer:

<s:ItemRenderer xmlns:fx="http://ift.tt/rYUnH9" 
                xmlns:s="library://ns.adobe.com/flex/spark" 
                xmlns:mx="library://ns.adobe.com/flex/mx" >

<fx:Script>
        <![CDATA[

            protected function onChange(event:Event):void
            {
                trace("checked");
            }

        ]]>
    </fx:Script>

<s:CheckBox id="chkBox" selected="{data.selected}" change="onChange(event)"  />
<s:Label id="lblCon" fontSize="14" text="{data.test}"  />

</s:ItemRenderer>

I want CheckBox change and label click event.
But When i open Dropdown and try to click on checkbox. DropDown is closed(no worry) and checkbox is not checked.

Any help is appreciated.