jquery-easyui的treegrid没法得到后台数据

jquery-easyui的treegrid无法得到后台数据
$('#tg').treegrid({ 
     title:'角色列表',
     iconCls: 'icon-edit',  
             rownumbers: true,  
             animate: true,  
             collapsible: true,  
             fitColumns: true,  
             url: 'roleList.action',  
             idField: 'id',  
             treeField: 'name',  
             pagination:true,
             showFooter: false,   
        columns:[[  
            {title:'角色名称',field:'name',width:100},  
            {field:'des',title:'描述',width:100,align:'right'},  
            {field:'modify',title:'修改时间',width:100},  
            {field:'operate',title:'操作',width:100,align:'center',formatter:formatOperate}  
        ]]  
    }); 

后台JSONArray ja = JSONArray.fromObject(roleList); 
JSONObject jo=new JSONObject();  

  jo.put("total", roleList.size());  

  jo.put("rows", ja);  
  System.out.println(jo.toString());
PrintWriter out = response.getWriter();
out.print(jo.toString());
out.flush();
out.close();
把json数据写到流里面，浏览器中能得到数据，但是从前台部能跳转到ACTION里面，请高手指点
[解决办法]
pagination:true,去掉