我正在.net 3.5中创建水晶报表，但收到以下错误..

无法加载文件或程序集``System.Web.Extensions，Version = 2.0.0.0，Culture = neutral，PublicKeyToken = 31bf3856ad364e35''或其依赖项之一.找到的程序集的清单定义与
不匹配

背后的代码

Could not load file or assembly ''System.Web.Extensions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'' or one of its dependencies. The located assembly''s manifest definition does not match the


Code Behind

protected void Page_Load(object sender, EventArgs e)
   {
       ReportDocument reportdocument = new ReportDocument();
       reportdocument.Load(Server.MapPath("CrystalReport.rpt"));

       CrystalReportViewer1.ReportSource = reportdocument;
   }

来源详细信息

source details

<div>

       <CR:CrystalReportViewer ID="CrystalReportViewer1" runat="server"

           AutoDataBind="True" EnableDatabaseLogonPrompt="False" Height="1039px"

           ReportSourceID="CrystalReportSource1" Width="901px" />
       <CR:CrystalReportSource ID="CrystalReportSource1" runat="server">
           <Report FileName="CrystalReport.rpt">
           </Report>
       </CR:CrystalReportSource>

   </div>