title: Type or namespace 'DocumentFormat' could not be found - only on build - but intellisense shows the type as available
body: <p>I have downloaded the <code>Power Tools for Open XML</code> from the following website:-</p>
  
  <p><a href="https://powertools.codeplex.com/" rel="nofollow">https://powertools.codeplex.com/</a></p>
  
  <p>I open the solution in VS2012 and then update the references - <code>DocumentFormat.OpenXml</code> and <code>WindowsBase</code>. </p>
  
  <p>The problem is:-</p>
  
  <p>The Visual Studio intellisense shows the namespace when I start typing it at the top of class, but when I build the solution, I get the following error from all the classes where this namespace is used-</p>
  
  <p><code>The type or namespace 'DocumentFormat' could not be found.</code></p>