ext combox 下拉框不出现自动提示,自动选中的解决方法

var comboxContractType = new Ext.form.ComboBox({
name:logisticsId,
fieldLabel:物流公司,
displayField:logisticsName,
valueField:logisticsId,
emptyText:请选择,
width:330,
editable:true,
allowBlank:false,
mode:local,
loadingText:loading...,
hiddenName:logisticsId,
//pageSize:10,
selectOnFocus: true,
triggerAction:all,
store:comboxContractTypeStore = new Ext.data.JsonStore({
url:/pcms/dictionary/logistics.do?method=findLogistics,
root:Datas,
totalProperty: TotalRecords,
fields:[
{name:logisticsId, mapping:logisticsid},
{name:logisticsName, mapping:shortname}
]
})
});
comboxContractTypeStore.load({params:{start:0,limit:100}});