title: Element 'RadGrid' is not a known element
body: <p>I'm trying to use the Telerik RadGrid, but I'm getting the following warning:</p>
  
  <blockquote>
    <p>"Element 'RadGrid' is not a known element.  This can occur if there is
    a compilation error in the Web site, or the web.config file is
    missing."</p>
  </blockquote>
  
  <p>Here are some things that I've already checked:</p>
  
  <ul>
  <li>The web.config file isn't missing, and there aren't any other
  compilation problems on the page.</li>
  <li>The Telerik.Web.UI dll is in the GAC, and the project's references
  point to that file.  No Telerik dlls in the bin folder.</li>
  <li>The assembly is added in the web.config using this in the assemblies
  section:   <code>&lt;add assembly="Telerik.Web.UI, Version=2011.1.413.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4"/&gt;</code></li>
  <li>The properties of the RadGrid work, so Visual Studio is able to
  figure out what the object is</li>
  <li>The page runs normally, I just have this annoying set of
  warnings.</li>
  <li>I tried adding an @Register statement for the Telerik assembly on the page, but got no change</li>
  <li>I tried clean/rebuild, but no change</li>
  <li>I tried restarting Visual Studio, no change</li>
  <li>I tried restarting the machine, no change</li>
  </ul>
  
  <p>EDIT:
  Here's the markup I'm using.</p>
  
  <pre><code>&lt;%@ Page Title="" Language="C#" MasterPageFile="~/masterPages/ActionAreaSinglePanelMaster.Master" AutoEventWireup="true" CodeBehind="overview.aspx.cs" Inherits="Compass.overview" %&gt;
  
  
  &lt;asp:Content ID="PanelHeaderContent" ContentPlaceHolderID="PanelHeaderPlaceholder" runat="server"&gt;
      &lt;p&gt;Panel header&lt;/p&gt;
  &lt;/asp:Content&gt;
  
  
  &lt;asp:Content ID="PanelContent" ContentPlaceHolderID="PanelDataPlaceholder" runat="server"&gt;
      &lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;&lt;/asp:ScriptManager&gt;
      &lt;script src="../Scripts/jquery-1.4.1.js" type="text/javascript"&gt;&lt;/script&gt;
      &lt;script src="../Scripts/radGridLayout.js" type="text/javascript"&gt;&lt;/script&gt;
      &lt;script type="text/javascript"&gt;
          panelGridID = "&lt;%=panelGrid.ClientID %&gt;";
      &lt;/script&gt;
  
      &lt;asp:ObjectDataSource ID="BundleItemsSource" runat="server" TypeName="Compass.Data.CompassUI" SelectMethod="BundleDataSet"&gt;
          &lt;SelectParameters&gt;
              &lt;asp:QueryStringParameter Name="bundleID" QueryStringField="bundle" /&gt;
          &lt;/SelectParameters&gt;
      &lt;/asp:ObjectDataSource&gt;
  
      &lt;telerik:RadGrid id="panelGrid" runat="server" DataSourceID="BundleItemsSource" Height="100%" Width="100%"&gt;
          &lt;ClientSettings&gt;
              &lt;Scrolling AllowScroll="True" UseStaticHeaders="True" /&gt;
              &lt;ClientEvents OnGridCreated="gridCreated" /&gt;
          &lt;/ClientSettings&gt;
      &lt;/telerik:RadGrid&gt;
  
  &lt;/asp:Content&gt;
  </code></pre>