EXT4.0 问题，选择年份的地方为什么在IE浏览器运行没问题，在火狐浏览器运行有问题呢？

Ext.onReady(function()
    {
  var data=
      [
          ['2012年8月1日','10','200'],
          ['2012年8月2日','10','200'],
          ['2012年8月3日','12','200'],
          ['2012年8月4日','12','200'],
          ['2012年8月5日','12','200'],
          ['2012年8月6日','12',''],
          ['2012年8月7日','10',''],
          ['2012年8月8日','12','200']
      ]; 
              
        var data1=
            [
                ['1','育新小区'],
                ['2','东村家园'],
                ['3','富力桃园']
            ];  
        
        var data2= new Array();     
             data2[0] = 
                 [
                     ['11','1单元'],
                     ['12','2单元']
                 ];     
             data2[1] = 
                 [
                     ['21','3单元'],
                     ['22','4单元']
                 ];
             data2[2] = 
                 [
                     ['31','5单元'],
                     ['32','6单元']
                 ];  
              
        monthsStore = Ext.create('Ext.data.Store', {
            fields: ['name', 'num'],
            data: (function() {
                var data = [];
                Ext.Array.forEach(Ext.Date.monthNames, function(name, i) {
                    data[i] = {name: name, num: i + 1};
                });
                return data;
            })()
        });
        
  var store=new Ext.data.SimpleStore({
      data:data,
   fields:["id","pingguo","caomei"]});
  
  var store1=new Ext.data.SimpleStore({
      data:data1,
      fields:['xiaoqu','xiao']});
  
  var store2=new Ext.data.SimpleStore({
      data:[],
      fields:['value','text']});
  
  var grid=new Ext.grid.GridPanel({
      renderTo:Ext.getBody(),
      height:200,
      width:800,
      stripeRow:true,
      loadMask:true,
      
      tbar: 
      [
          {
              xtype:'label',
              text:'小区：'
          },
          
          {
              xtype:"combo",
              mode:'local',
              valueField:'xiaoqu',
              displayField:'xiao',
              width: 50,
              store:store1,
              listeners:
              {
         'select' : function(cb)
         {
          var selectedId = cb.getValue();
          store2.loadData(data2[selectedId-1]);
         }
        }
    },
    
          {
              xtype:'label',
              text:'单元：'
          },
          
          {
              xtype:"combo",
              mode:'local',
              valueField:'value',
              displayField:'text',
              width: 50,
              store:store2
          },
          
          {
              xtype:"tbseparator"
          },
          
                {
                    xtype: 'fieldcontainer',
                    fieldLabel: '月份',
                    labelWidth: 25,
                    autoHeight : true,
                    layout: 'hbox',
                    width: 200,
                    items: 
                    [
                        {
                            xtype: 'numberfield',
                            name: 'ccExpireYear',
                            hideLabel: true,
                            width: 80,
                            value: new Date().getFullYear()
                        },
                        
                        {
                            xtype: 'combobox',
                            name: 'ccExpireMonth',
                            displayField: 'name',
                            valueField: 'num',
                            queryMode: 'local',
                            emptyText: 'Month',
                            hideLabel: true,
                            width: 80,
                            margins: '0 6 0 0',
                            store: monthsStore,
                            flex: 1,
                            forceSelection: true
                        }
                    ]
                } 
            ],
                
   columns:
   [
    {
        header:"日期",
        flex:1,
     dataIndex:"id"
       },
     
    {
        header:"苹果树",
        flex:1,
     dataIndex:"pingguo"
    },
     
    {
        header:"草莓",
        flex:1,
     dataIndex:"caomei"
    }
   ],
     
   store:store
   });
  });