Preencher comboBox

não consigo preencher minha comboBox. no java ta tudo ok, o problema acho que é no flex. segue meu codigo.

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<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
	xmlns:entidade="entidade.*"
	creationComplete="buscar() "  xmlns:local="*">

	<mx:Script>
		<![CDATA[
			import mx.controls.List;
						import mx.controls.dataGridClasses.DataGridColumn;
						import mx.utils.StringUtil;
						import mx.managers.DragManager;
						import mx.controls.Alert;
						import mx.containers.Panel;
						import mx.events.DragEvent;
						import mx.rpc.events.FaultEvent;
						import entidade.NotaFiscal;
						import entidade.Produto;
						import entidade.ItemNota;
						import mx.rpc.events.ResultEvent;
						import mx.collections.ArrayCollection;
						
						
						[Bindable]
						private var listaDeNotas:ArrayCollection;
						
						[Bindable]
						private var listaDeItens:ArrayCollection;
						
						[Bindable]
						private var listaDeProdutos:List;
						
						private function salvarResult(event:ResultEvent):void{
							if(event.result != null){
								notaFiscal = event.result as NotaFiscal;
								buscar();
							}
						}
						
						private function inserirItensResult(event:ResultEvent):void{
							if(event.result != null){
								itemNota = event.result as ItemNota;
							}
						}
						
						private function excluirResult(event:ResultEvent):void{
							limpar();
							buscar();
						}
						
						private function alterarResult(event:ResultEvent):void{
							if(event.result != null){
								notaFiscal = event.result as NotaFiscal;
								buscar();
							}
						}
						
						private function listarResult(event:ResultEvent):void{
							if(event.result != null){
								
								listaDeNotas = event.result as ArrayCollection;
								listaDeItens = event.result as ArrayCollection;
								//listaDeProdutos = event.result as ArrayCollection;
							}else{
								listaDeNotas = new ArrayCollection();
								listaDeItens = new ArrayCollection();
								//listaDeProdutos = new ArrayCollection();
								
							}
						}
						
						private function listarResultProdutos(event:ResultEvent):void{
							if(event.result != null){
								listaDeProdutos = event.result as List;
							}else{
								listaDeProdutos = new List();
							}
							
						}
						
						private function erroFault(event:FaultEvent):void{
							Alert.show("Erro: " + event.fault.faultDetail.toString());
						}
						
						public function salvar():void{
							roNotaFiscal.salvar(notaFiscal);
						}
						
						public function alterar():void{
							roNotaFiscal.alterar(notaFiscal);
						}
						
						public function excluir():void{
							roNotaFiscal.excluir(notaFiscal);
						}
						
						public function buscar():void{
							roNotaFiscal.buscar();
						}
						
						public function inserirItens():void{
							roNotaFiscal.inserirItens();
						}
						
						public function buscarPorNotaFiscal():void{
							roNotaFiscal.buscarPorNotaFiscal();
						}
						
						public function listarProdutos():void{
							roProduto.listar();
						}
						
						public function listarItens():void{
							roNotaFiscal.pegaItens();
						}
						
						public function limpar():void{
							notaFiscal = new NotaFiscal();
						}
						
						private function dragEnterHandler(event:DragEvent):void{
							var dropTarget:Panel=Panel(event.currentTarget);
							DragManager.acceptDragDrop(dropTarget);
						}
						
						private function dragDropHandler(event:DragEvent):void{
							notaFiscal = event.dragSource.dataForFormat("items")[0] as NotaFiscal;
						}
						
		]]>
	</mx:Script>
	
	<entidade:NotaFiscal id="notaFiscal"/>
	<entidade:Produto id="produto"/>
	<entidade:ItemNota id="itemNota"/>
	
	
	
	
	<mx:SeriesZoom id="seriesZoom" duration="2000"/>
				
	<mx:Binding source="Number(tiIdNota.text)" destination="notaFiscal.id"/>
	<mx:Binding source="data(tiDataEmissao.text)" destination="notaFiscal.dataEmissao"/>
	
	<mx:Panel  width="100%" height="177" layout="absolute" 
		title="Cadastro de Notas"
		dragEnter="dragEnterHandler(event);"
		dragDrop="dragDropHandler(event);">
		<mx:Label x="10" y="10" text=" Id: #"/>
		<mx:Label x="10" y="38" text="Data de Emissao: *"/>
		<mx:TextInput x="56" y="8" width="81" enabled="false" editable="false" id="tiIdNota"
							text="{notaFiscal.id == 0 || isNaN(notaFiscal.id) ? null : notaFiscal.id}"/>
		
		<mx:TextInput x="133" y="36" maxChars="100" width="246" id="tiDataEmissao" text="{notaFiscal.dataEmissao}"/>
		<mx:ComboBox id="cbProdutos" 
		 dataProvider="{listaDeProdutos}"  labelField="{produto.nome}" x="77" y="69" width="150">
		
		</mx:ComboBox>
		<mx:Label x="10" y="73" text="Produtos:"/>
		
		<mx:ControlBar>
		
			<mx:Button label="Salvar" click="salvar()"/>
			<mx:Button label="Excluir" click="excluir()"/>
			<mx:Button label="Alterar" click="alterar()"/>
			<mx:Button label="Limpar" click="limpar()"/>
			<mx:Button label="Inserir Iten" click="cbProdutos.selectedItem "/>
			
		</mx:ControlBar>
		
	</mx:Panel>
	
	<mx:RemoteObject id="roNotaFiscal" destination="notaFiscal">
	
		<mx:method name="salvar"
			fault="erroFault(event)"
			result="salvarResult(event)"/>
		
		<mx:method name="alterar"
			fault="erroFault(event)"
			result="alterarResult(event)"/>
			
		<mx:method name="excluir"
			fault="erroFault(event)"
			result="excluirResult(event)"/>
			
		<mx:method name="buscar"
			fault="erroFault(event)"
			result="listarResult(event)"/>
			
		<mx:method name="pegaItens"
			fault="erroFault(event)"
			result="listarResult(event)"/>	
			
		
			
		<mx:method name="inserirItens"
			fault="erroFault(event)"
			result="inserirItensResult(event)"/>
			
	</mx:RemoteObject>
	
	<mx:RemoteObject id="roProduto" destination="produto">
		<mx:method name="listar"
			fault="erroFault(event)"
			result="listarResultProdutos(event)"/>
			
	</mx:RemoteObject>
	
	<mx:Panel x="10" y="185" width="462" height="138" layout="absolute" title="Lista de Notas Fiscais">
		<mx:DataGrid x="0" y="0" width="432" height="120"
			dragEnabled="true"
			dataProvider="{listaDeNotas , listaDeItens}"
			id="dgNotas">
			<mx:columns>
				<mx:DataGridColumn headerText="Id_NotaFiscal" dataField="id" width="100"/>
				<mx:DataGridColumn headerText="Data_Emissao" dataField="dataEmissao" width="100"/>
				<mx:DataGridColumn headerText="Id_Item" dataField="{itemNota.id}"/>
				<mx:DataGridColumn headerText="Id_Produto" dataField="{produto.id}"/>
				<mx:DataGridColumn headerText="Quantidade" dataField="{itemNota.quantidade}"/>
			</mx:columns>
		</mx:DataGrid>
	
	</mx:Panel>
	
	
	
	
</mx:Application>