EXTJS中什么原因导致从服务器读取出来的数据不能显示在列表里面呢？：报错

Ext.QuickTips.init();
        var cm = new Ext.grid.ColumnModel([  
            {header:'编号',dataIndex:'paramId'},  
	        {header:'编码',dataIndex:'paramCode'},
	        {header:'类型',dataIndex:'paramType'},
	        {header:'值',dataIndex:'paramValue'},
	        {header:'描述',dataIndex:'paramDesc'},
	        {header:'备注',dataIndex:'remark'}  
        ]);  
          
       var proxy = new Ext.data.HttpProxy({url:"showParamList.action"});  
       //var proxy = new Ext.data.MemoryProxy(data);  
          
        var record = Ext.data.Record.create([  
            {name:'paramId',type:"int",mapping:'paramId'},  
	        {name:'paramCode',type:'string',mapping:'paramCode'},
	        {name:'paramType',type:'string',mapping:'paramType'},
	        {name:'paramValue',type:'string',mapping:'paramValue'},
	        {name:'paramDesc',type:'string',mapping:'paramDesc'} ,
	        {name:'remark',type:'string',mapping:'remark'}   
        ]);  
          
        var reader = new Ext.data.JsonReader({
			totalProperty: 'totalProperty',
            id:'paramId', 
            result:'results'   
        },record);  
          
        var store = new Ext.data.Store({  
            proxy:proxy,  
            reader:reader  
        });  
          
        var grid = new Ext.grid.GridPanel({  
            title:'表格',  
            cm:cm,  
            store:store,  
            width:800,  
            height:300,  
            loadMask:true,
	        autoShow:true,
	        columnLines:true,
	        header:true,
	        frame:true,
            autoExpandColumn:2,  
            renderTo:Ext.getBody(),
            bbar: new Ext.PagingToolbar({
                pageSize: 20,//显示多少页
                store: this.store,
                displayInfo: true,
                displayMsg: "显示第{0}-{1}条,共有{2}条记录",
                emptyMsg: "没有记录"
            })
        });   
        store.load({params:{start:0,limit:5}});