asp.net mvc4中easyui datagrid获取不到后台的数据

<link rel="stylesheet" type="text/css" href="~/Content/easyui.css">
<link rel="stylesheet" type="text/css" href="~/Content/icon.css">
<script src="~/Content/AdminLTE/js/jquery-2.0.0.min.js"></script>
<script type="text/javascript" src="~/Content/jquery.easyui.min.js"></script>

 <script>
    function InitGrid() {
        $('#grid').datagrid({   
            url: '/Home/GetList',   
            title: '功能菜单',
            iconCls: 'icon-view',
            height: 650,
            width: function () { return document.body.clientWidth * 0.9 },
            nowrap: true,
            autoRowHeight: false,
            striped: true,
            collapsible: true,
            pagination: true,
            pageSize: 100,
            pageList: [50, 100, 200],
            rownumbers: true,
            //sortName: 'ID',    //根据某个字段给easyUI排序
            sortOrder: 'asc',
            remoteSort: false,
            idField: 'id',
            queryParams: queryData,  //异步查询的参数
            columns: [[
                 { title: 'id', field: 'id', width: 80 },
            ]]
        });
    }

    $(document).ready(function () {
        InitGrid();
    });
</script>

  <table id="grid" style="width: 1024px" title="用户操作"></table>

运行后发现没有数据，在后台action中设置断点后，运行发现没有触发断点，求大神指点一下是什么原因
后台代码

         public JsonResult GetList()
        {
            string a = "{\"total\":10,\"rows\":[{\"id\":\"a\"},{\"id\":\"b\"}]}";
            return Json(a, JsonRequestBehavior.AllowGet);
        }