解决Asp.net中的Chart控件运行出现错误提示“ ChartImg.axd 执行子请求时出错”

<?xml version="1.0"?>
<!--
  有关如何配置 ASP.NET 应用程序的详细消息，请访问
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
    <appSettings>
  <add key="ChartImageHandler" value="storage=file;timeout=20;dir=c:\TempImageFiles\;" />
 </appSettings>
 <system.webServer>
  <handlers>
   <remove name="ChartImageHandler" />
   <add name="ChartImageHandler" preCondition="integratedMode" verb="GET,HEAD,POST"
    path="ChartImg.axd" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
  </handlers>
 </system.webServer>
 <connectionStrings>
        <add name="testConnectionString" connectionString="Data Source=.;Initial Catalog=test;User ID=sa;Password=******" providerName="System.Data.SqlClient"/>
    </connectionStrings>
    <system.web>
        <httpHandlers>
   <add path="ChartImg.axd" verb="GET,HEAD,POST" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    validate="false" />
  </httpHandlers>
  <pages>
   <controls>
    <add tagPrefix="asp" namespace="System.Web.UI.DataVisualization.Charting"
     assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
   </controls>
  </pages>
  <compilation debug="true" targetFramework="4.0">
            <assemblies>
                <add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/></assemblies></compilation>
    </system.web>
</configuration>