title: Error: 'AjaxControlToolkit' is undefined but only on IIS
body: <p>I have an ASP.NET application, which used AjaxControlToolkit. It works fine when I run it from VS using development web server and also working when deployed to testing server.
  Now I decided to try it using IIS on my computer. I created Virtual Directory and published site there. But if I'm running it from IIS, I get the following error:</p>
  
  <p><img src="https://i.stack.imgur.com/dxqz0.png" alt="Error: &#39;AjaxControlToolkit&#39; is undefined"></p>
  
  <p>The same files are located in the bin folder and AjaxControlToolkit.dll is there.</p>
  
  <p>I think maybe I need to change some settings in IIS?</p>