通用处理程序在使用javascript重新加载时不加载更多内容

Question

这是我的javascript加载更多内容，只使用填充gridview的存储过程显示接下来的10条记录

<script>
       var prev = 0;
       function Loadmore() {

           //get last Order Id to track next fetch
           var OrderIdLast = $("#tblOrders1 tr:last").children("td:first").html();

           //get last table row in order to append the new result set increment
           var trLast = $("#tblOrders1 tr:last");
           if (parseInt(OrderIdLast, 10) > parseInt(prev, 10)) {
               prev = OrderIdLast;
               //make a async call to fetch the incremental results    
               $.post("Handler5.ashx?lastOrderId=" + OrderIdLast, function (data) {
                   if (data != null) {
                       //append new result set to last row
                       trLast.after(data);
                   }
               });
           }
       }
    </script>

 <input type="button" value="Load"  onclick="Loadmore()" runat="server"/>

但是当我第二次重新输入输入时，它无法加载下一组数据

我做错了什么？