Error 10 Object reference not set to an instance of an object.

<system.web>
    <httphandlers>
      <add path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
        validate="false" />
    </add></httphandlers>
    <compilation debug="true" targetframework="4.0">
      <assemblies>
        <add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Web.Extensions.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="Microsoft.ReportViewer.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="Microsoft.Build.Framework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Management, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
      </assemblies>
      <buildproviders>
        <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
      </buildproviders>
    </compilation>
    <authentication mode="Forms">
      <forms loginUrl="~/UI/LogInUI.aspx" defaultUrl="~/UI/LogInUI.aspx" slidingExpiration="true" timeout="20" path="/" requireSSL="false" enableCrossAppRedirects="false">
        <credentials passwordformat="SHA1">
        </credentials>
      </forms>
    </authentication>
    <!--<authentication mode="Forms">
      <forms defaultUrl="~/View/Login.aspx" loginUrl="~/View/Login.aspx" slidingExpiration="true" timeout="20"></forms>
    </authentication>-->
    <authorization>
    </authorization>
  </system.web>
  <system.webserver>
    <validation validateintegratedmodeconfiguration="false" />
    <handlers>
      <add name="ReportViewerWebControlHandler" precondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
    </handlers>
  </system.webserver>