title: Cannot add reference to WixUIExtension.dll, WixUtilExtension.dll and WixNetFxExtension.dll from Visual Studio 2008
body: <p>I am using WiX 3.7 with <a href="http://en.wikipedia.org/wiki/Microsoft_Visual_Studio#Visual_Studio_2008">Visual&nbsp;Studio&nbsp;2008</a>, and I am trying to add a reference to few WiX DLL files so that I can work with a UI in my installation. However, I get the following error for each of the following files that I add a reference to:</p>
  
  <ul>
  <li>WixUIExtension.dll</li>
  <li>WixUtilExtension.dll</li>
  <li>WixNetFxExtension.dll</li>
  </ul>
  
  <blockquote>
    <p>A reference to C:\Program Files (x86)\WiX Toolset v3.7\WixNetFxExtension.dll could not be added. Please make sure that the file is accessible, and that it is a valid WiX reference.</p>
  </blockquote>
  
  <p>Also, before I started thinking about moving to a UI based interface, there was no issue with the WiX installer that I am creating; it compiles and installs absolutely fine.</p>
  
  <p>Please note that I am able to add reference to the same files in Visual Studio 2012 and Visual Studio 2010.</p>