Flex atualizar item render na tabela

Assuntos Gerais
#1

quando recarrego o ArrayCollection de um data grid no flex 3 , a imagem do itemRenderer da coluna nao atualiza.

grid

<mx:DataGrid editable="true"  id="gridPrincipal" width="100%" height="80%" dataProvider="{listaNFE}" y="49" fontSize="11" x="-10">
		<mx:columns>
			<mx:DataGridColumn headerText="Nº Nota" dataField="numeroNota" textAlign="center" width="90"/>
			<mx:DataGridColumn headerText="Destinatário" dataField="destinatario" textAlign="center"/>
			<mx:DataGridColumn headerText="Data Emissão" dataField="dataEmissao" textAlign="center" width="120"/>
			<mx:DataGridColumn headerText="Valor Total"  labelFunction="labelValor" textAlign="center" width="120"/>
			<mx:DataGridColumn headerText="Status"  itemRenderer="br.com.monitor.renderer.status_nfe_renderer" textAlign="center" width="90" rendererIsEditor="true" dataField="status" editorDataField="status"/>
            <mx:DataGridColumn headerText=" " itemRenderer="br.com.monitor.renderer.email_renderer" width="20" textAlign="center" rendererIsEditor="true"/>
            <mx:DataGridColumn headerText=" "  itemRenderer="br.com.monitor.renderer.print_renderer" width="20" textAlign="center" rendererIsEditor="true"/>
            <mx:DataGridColumn headerText=" "  itemRenderer="br.com.monitor.renderer.visualiza_nfe_renderer" width="20" textAlign="center" rendererIsEditor="true"/>
		</mx:columns>
	</mx:DataGrid>

rederer status

<mx:Script>
		<![CDATA[
			[Bindable]
			[Embed(source='br/com/monitor/assets/bolaverde.png')]
			public var bolaVerde : Class ;
			
			[Bindable]
			[Embed(source='br/com/monitor/assets/bolavermelha.png')]
			public var bolaVermelha : Class ;
			
			[Bindable]
			[Embed(source='br/com/monitor/assets/bola_bronze.png')]
			public var bolaBronze : Class ;
		
			[Bindable]
				private var _objBind:Object;
 
				override public function set data(value:Object):void{
				
			super.data = value;
			_objBind = value;
		
}
				
			public function open():void {
				if (_objBind.status == 100){
					img.source = bolaVerde;
					img.toolTip = _objBind.status.toString()+" - "+_objBind.motivo;
				}else if (_objBind.status == 0){
				    img.source = bolaBronze;
					img.toolTip = "NF em processamento"
				}else{
					img.source = bolaVermelha;
					img.toolTip = _objBind.status.toString()+" - "+_objBind.motivo;;
				}
			}
			
		]]>
	</mx:Script>
	
	
	<mx:Image id="img" x="37" y="0" width="16" height="16" creationComplete="{open()}" />
#2