easyui combobox默认选中项

今天写前端代码发现combobox还挺难搞，

$("#select_Dic").combobox({
                        url: "http://www.cnblogs.com/Ajax/sys/WebServiceBase.ashx?Method=GetRefItems", //获取所有私有域
                        valueField: "Code",
                        textField: "Name",
                        panelHeight: "auto",
                        editable: false, //不允许手动输入
                        onLoadSuccess: function () { //数据加载完毕事件
                            var data = $('#select_Dic').combobox('getData');
                            if (data.length > 0) {
                                $("#select_Dic").combobox('select', data[0].value);
                            }
                        }
                    });