ASP.default_aspx.GetTypeHashCode()”: 没有找到适合的方法来重写

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;namespace SetPosByAttr
{
    public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
    {
        public string m_ADFCallbackFunctionString;
        protected void Page_Load(object sender, EventArgs e)
        {
            m_ADFCallbackFunctionString = Page.ClientScript.GetCallbackEventReference(this, "message",
            "processCallbackResult", "context", "postBackError", true);
        }
         public string GetCallbackResult()
                {
                    return "Callback result";
                }
        public void RaiseCallbackEvent(string eventArgs)
        {
            System.Collections.IEnumerable.func_enum = null;
            //获取当前map1控件中所有的functionality
            func_enum = Map1.GetFunctionalities();            System.Data.DataTable datatable;
            //对所有的functionality进行遍历
            foreach (ESRI.ArcGIS.ADF.Web.DataSources.IGISFunctionality gisfunctionality in func_enum)
            {
                ESRI.ArcGIS.ADF.Web.DataSources.IGISDataSource gisresource = null;
                //得到该functionality的resource
                gisresource = gisfunctionality.Resource;
                //判断该resource是否支持IQueryFunctionality
                bool support = false;
                supported = gisresource.SupportsFunctionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality));
                if (supported)
                {
                    ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality qfunc;
                    qfunc = (ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality)gisresource.CreateFuntionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality), null);
                    string[] lids;
                    string[] lnames;
                    //获得图层的layerId和layerName，GetQueryableLayers的重载方法可以指定图层类型
                    qfunc.GetQueryableLayers(null, out lids, out lnames);                    int selindex = -1;
                    for (int i = 0; i < lids.Length; i++)
                    {
                        if (lnames[i] == "变压器")
                        {
                            //找到变压器图层的序号
                            selindex = i;
                            break;
                        }
                    }                    if (selindex > -1)
                    {
                        //设置过滤器的过滤条件
                        ESRI.ArcGIS.ADF.Web.SpatialFilter spatialfilter = new ESRI.ArcGIS.ADF.Web.SpatialFilter();
                        spatialfilter.ReturnADFGeometries = true;
                        spatialfilter.MaxRecords = 100;
                        spatialfilter.WhereClause = "name like '%" + eventArgs + "%'";                        //对指定的图层进行查询，查询的结果保存为
                        datatable = qfunc.Query(null, lids[selindex], spatialfilter);
                        if (datatable != null)
                        {
                            if (datatable.Rows.Count > 0)
                            {
                                for (int j = 0; j < datatable.Columns.Count; j++)
                                {
                                    if (datatable.Columns[j].DataType == typeof(ESRI.ArcGIS.ADF.Web.Geometry.Geometry))
                                    {
                                        ESRI.ArcGIS.ADF.Web.Geometry.Point pnt = (ESRI.ArcGIS.ADF.Web.Geometry.Point)datatable.Rows[0][j];
                                        Map1.CenterAt(pnt);
                                        m_ADFCallbackFunctionString = Map1.CallbackResults.ToString();
                                        return;
                                    }
                                }                            }
                            else
                            {
                                object[] ob = new object[1];
                                string sa = "alert('没有找到该变压器');";
                                ob[0] = sa;
                                ESRI.ArcGIS.ADF.Web.UI.WebControls.CallbackResult callbackresult = new ESRI.ArcGIS.ADF.Web.UI.WebControls.CallbackResult(null, null, "Javascript", ob);
                                Map1.CallbackResults.Add(callbackresult);
                                m_ADFCallbackFunctionString = Map1.CallbackResults.ToString();                            }
                        }
                    }
                }            }        }
    }
}我复制书上的代码，自己运行就出现错误，愁了一天了没解决，求求救啊
错误 3 “ASP.default_aspx.GetTypeHashCode()”: 没有找到适合的方法来重写  
错误 4 “ASP.default_aspx.ProcessRequest(System.Web.HttpContext)”: 没有找到适合的方法来重写  
错误 5 “ASP.default_aspx”不实现接口成员“System.Web.IHttpHandler.IsReusable”