用ExtJS4写的一个combobox下拉框里面木有值 求大侠指点

Ext.onReady(function(){


var poststore=Ext.create('Ext.data.Store',{fields: ['province','postNum'],
date:[
{province:'浙江',postNum:'1'},
{province:'湖南',postNum:'2'},
{province:'江苏',postNum:'3'},
{province:'安徽',postNum:'4'},
{province:'江西',postNum:'5'}
]
}); var com=new Ext.form.ComboBox({
listCofig:{
emptyText:'未找到匹配值',
maxHeight:60
},
name:'post',
fieldLabel:'邮政编码',
triggerAction:'all',
store:poststore,
displayField:'province',
valueField:'postNum',
queryMode:'local',
forceSelection:true,
typeAhead:true,
value:'4'
})
Ext.create('Ext.form.Panel',{
title:'本地数据源示例0000',
renderTo:'store',
bodyPadding:5,
frame:true,
height:100,
width:270,
defaults:{
labelSpeparator:':',
labelWidth:70,
width:200,
labelAlign:'left'
},
items:com
});


})
这是js代码
jsp页面有个div id为store  页面展示正确，就是啦框木有值