一个ext combobox的奇怪问题，选择一次后就只剩下一个options了，求高手指教

 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">  
    
    <title>My JSP 'layerTree.jsp' starting page</title>
    
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">    
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
 <link rel="stylesheet" type="text/css" href="gisindex/public/com/ext/resources/css/ext-all.css"/><!-- ext样式 -->
<link rel="stylesheet" type="text/css" href="gisindex/public/com/css/task.css"/>  <!-- 图标定义的css -->
<link rel="stylesheet" type="text/css" href="gisindex/public/com/css/cls.css"/> 
    <!-- ext系统库 -->
    <script type="text/javascript" src="gisindex/public/com/ext/js/ext-base.js"></script>
    <script type="text/javascript" src="gisindex/public/com/ext/js/ext-all.js"></script>
<script type="text/javascript" src="gisindex/public/com/ext/js/map/xmlTree.js"></script> <!-- xml解析为tree工具类 -->
  <!-- 调用flex端接口js -->
 
   <script type="text/javascript" src="bridge/FABridge.js"></script>
   <script type="text/javascript" src="bridge/maintenance/maintenance.js"></script>
 <style type="text/css">
*{
scrollbar-base-color:#fcfcfb；
scrollbar-face-color:#fcfcfb;
scrollbar-highlight-color:rgb(252,252,251);
scrollbar-shadow-color:rgb(167,166,163);
scrollbar-3dlight-color:#a7a6a3;
scrollbar-arrow-color:rgb(252,252,251);
scrollbar-track-color:#fcfcfb;
scrollbar-darkshadow-color:rgb(252,252,251)
}
 .butcls{
text-algin:right; margin-left:130px;
}
  </style>
  <script type="text/javascript">
  
  Ext.onReady(function() {
     Ext.BLANK_IMAGE_URL='gisindex/public/com/s2.gif';
var tree_p;
Ext.QuickTips.init();
 
var record = new Ext.data.Record.create([
{name:'types'},
{name:'name'}
]);
var store = new Ext.data.Store({
proxy:new Ext.data.HttpProxy({url:'searchBarAction.do?method=getRange'}),
reader:new Ext.data.JsonReader({root:'rows'},record)
});
store.load();

var rangeCombo = new Ext.form.ComboBox({
id: 'searchArea',
 // fieldLabel:'范    围',
store:store,
displayField:'name',
valueField:'types', 
itemCls: 'all-field',
clearCls: 'allow-float',
hideLabel:true,
        allowBlank: false,
        forceSelection: true,
        typeAhead: true,
        triggerAction: '',
        emptyText: '范围',
        mode: 'local',
        selectOnFocus: true,
        width: 90 });
/**地区combobox**/
var rec = new Ext.data.Record.create([
{name:'cityName'}
]);
var sto = new Ext.data.Store({
proxy:new Ext.data.HttpProxy({url:'searchBarAction.do?method=getArea'}),
reader:new Ext.data.JsonReader({root:'rows'},rec)
});
sto.load();

var areaCombo = new Ext.form.ComboBox({
id: 'searchRegion',
 // fieldLabel:'地    区',
store:sto,
displayField:'cityName',
valueField:'cityName', 
hideLabel:true,
        allowBlank: false,
        forceSelection: true,
        typeAhead: true,
        triggerAction: '',
        emptyText: '地区',
        mode: 'local',
        itemCls: 'all-field',
clearCls: 'allow-float',
         selectOnFocus: true,
        width: 90

}); var formP=new Ext.form.FormPanel({
    region:'center',  
        frame:false,
        border:false,
        //
        bodyStyle:'background-color:#ffffff;margin:5px;padding:4px;border:1px solid #a1a1a1;',
        // autoHeight:true,     
         Height:180,
    items : [{ xtype:'textfield',
   width:180,
   hideLabel:true,
            //    fieldLabel: '关键字',
                name: 'searchName',
                id:'searchName',
                enableKeyEvents: true,
                listeners:{   
             specialkey:function(field,e){            
                if (e.getKey()==Ext.EventObject.ENTER){   
               
                   var range = rangeCombo.value;
       var area = areaCombo.value;
    window.parent.listSearch(this.getValue(),range,area);//调用main.js中的展开综合列表panel方法 
               }   
            },
            focus:function(text){
            var range = rangeCombo.value;
    var area = areaCombo.value;
             window.parent.listexpand(this.getValue(),range,area);//调用main.js中的展开综合列表panel方法 
            }   
        }                   },
                rangeCombo,
                areaCombo,
                 new Ext.Button({
id:'search_btn',
cls:'butcls',
text:'搜索',
itemCls: 'all-field',
clearCls: 'allow-float',
iconCls:'search',
handler:function(){
    var inputText = Ext.get("searchName").dom.value;
    var range = rangeCombo.value;
    var area = areaCombo.value;
window.parent.listSearch(inputText,range,area);//调用main.js中的展开综合列表panel方法 
}
})           
   ]  
 });
    /**给两个下拉框添加选择事件，使列表界面展开**/
  rangeCombo.on('select', function(combo, record, index){ // 选择事件
  var range = record.get('types');
  var area = areaCombo.value;
          window.parent.listexpand(this.getValue(),range,area);//调用main.js中的展开综合列表panel方法 
 });
 areaCombo.on('select', function(combo, record, index){ // 选择事件  
  var range = areaCombo.value;
  var area =  record.get('cityName');;
          window.parent.listexpand(this.getValue(),range,area);//调用main.js中的展开综合列表panel方法 
 });
  new Ext.Viewport({
        layout: 'border',   
        bodyStyle:'background-color:#e6e6e6;',    
        renderTo:document.body,
        animCollapse :true,
    items:[formP]
});   
 });
 </script>
  </head>
  
  <body>
   <div id="component" style="width:100%;height:100%"> </div>   
  </body>
</html>如题，rangeCombo areaCombo这两个下拉框 选择一次后就只剩下一个option了，不知有没有人遇到过这样的现象，求教！谢谢！