title: Referencing the correct System.Windows.Interactivity dll from Prism application
body: <p>I have a WPF Prism application that I'm building.  The application is to the point where  I want to be able to add EventTriggers to controls so I can call commands on the underlying view model.  However,  I can't seem to reference the correct DLLs to make the project run.  Currently, I'm referencing <code>Microsoft.Expression.Interactions</code> and <code>System.Windows.Interactivity</code> from the <code>C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0\Libraries</code> directory.  </p>
  
  <p>When I run the module, I get this error:</p>
  
  <blockquote>
    <p>Could not load file or assembly 'System.Windows.Interactivity,<br>
    PublicKeyToken=31bf3856ad364e35' or one of its dependencies.<br>
    The system cannot find the file specified.</p>
  </blockquote>
  
  <p>I checked the <code>System.Windows.Interactivity</code> assembly in reflector and can see that it references:</p>
  
  <ul>
  <li>mscorlib</li>
  <li>PresentationCore</li>
  <li>PresentationFramework</li>
  <li>System</li>
  <li>System.Core</li>
  <li>System.Xaml</li>
  <li>WindowsBase</li>
  </ul>
  
  <p>All the references point to the 4.0 framework.  I've referenced each from the .NET reference tab, making sure that each one is the 4.0 version.  All these references are being loaded from the <code>C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0</code> directory.  </p>
  
  <p>Is there another download I need for the <code>System.Windows.Interactivity</code> and <code>Microsoft.Expression.Interactions</code> assemblies to work in my environment?</p>