title: Why can't I find DataTemplates in merged resource dictionaries?
body: <p>In my MainWindow.xaml, I have the following reference to a ResourceDictionary:</p>
  
  <pre><code>&lt;Window.Resources&gt;
      &lt;ResourceDictionary&gt;
          &lt;ResourceDictionary.MergedDictionaries&gt;
              &lt;ResourceDictionary Source="MainSkin.xaml" /&gt;
          &lt;/ResourceDictionary.MergedDictionaries&gt;
      &lt;/ResourceDictionary&gt;
  &lt;/Window.Resources&gt;
  </code></pre>
  
  <p>In MainSkin.xaml, I define a datatemplate:</p>
  
  <pre><code>&lt;DataTemplate x:Key="TagTemplate"&gt;
     ...
  &lt;/DataTemplate&gt;
  </code></pre>
  
  <p>Deeper within my application, I attempt to use this data template:</p>
  
  <pre><code>&lt;ContentControl DataContext="{Binding Tag}" ContentTemplate="{StaticResource TagTemplate}"/&gt;
  </code></pre>
  
  <p>The code compiles successfully, but when I attempt to load a Page or UserControl that contains this StaticResource, I get an exception saying that the TagTemplate can't be found.</p>
  
  <p>What am I doing wrong?</p>