[]list控件内字体大小设置无效

private function updateItem(cell:Box, index:int):void{

			var itemImg:Image=cell.getChildByName("itemImg") as Image;

			var itemName:Label=cell.getChildByName("itemName") as Label;

			itemImg.skin=cell.dataSource.image_url;

			itemName.width=Number(itemName.text.length*20);

			itemName.height=20;

			itemName.fontSize =12;

			itemName.text=cell.dataSource.cat_name;

		}