title: ExtenderControlBase.cs not found when I am using the calendarExtender Ajax Control
body: <p>I got this error when I am trying to add an Ajax calendar.  I have downloaded the Ajax Control Toolkit from the CodePlex (I tried the new release (dec 2013 and the previous one).  I added a new tab in the ToolBox called Ajax Control Toolkit and Choose Items to add the AjaxControlToolkit.dll file to it.
  When I compiled I notice a new Bin folder in my Solution Explorer.  It contains two files AjaxControlToolkit.dll and the AjaxControlToolKit.pdb.</p>
  
  <p>I put this in my Web.config:</p>
  
  <pre><code>    &lt;pages&gt;
        &lt;controls&gt;
          &lt;add tagPrefix="asp"
             namespace="AjaxControlToolkit"
             assembly="AjaxControlToolkit" /&gt;
        &lt;/controls&gt;
      &lt;/pages&gt;
    &lt;/system.web&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>Here is my code </p>
  
  <pre><code>&lt;div class="center"&gt;
      &lt;div class="label"&gt; 
          &lt;asp:Label ID="lblDate1" runat="server" Text="Choose a date"&gt;&lt;/asp:Label&gt;
          &lt;asp:TextBox ID="txtDate1" runat="server" /&gt;
          &lt;asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"&gt; 
          &lt;/asp:ToolkitScriptManager&gt;
  
          &lt;asp:CalendarExtender ID="CalendarDate1" TargetControlID="txtDate1" 
             Format="dd/MM/yyyy" runat="server"&gt;&lt;/asp:CalendarExtender&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I am using a master page and a content place holder.  I am using C# VS Express 2013.  Also where do we get a free calendar.png image to add to the calendar box ?</p>
  
  <p>I saw it might be related with the Microsoft Ajax Minifier (<a href="http://www.nuget.org/packages/AjaxMin/" rel="nofollow">http://www.nuget.org/packages/AjaxMin/</a>) but this command is just working in a project.  I am in a Web Site not in a Project.  Here is the error "The current environment doesn't have a solution open" when I ran the following command "Install-Package AjaxMin" at the Package Manager Console.</p>