title: Triggers collection members must be of type EventTrigger
body: <p>I've created a UserControl, similar to the following:</p>
  <pre><code>&lt;UserControl&gt;
      &lt;StackPanel Orientation=&quot;Vertical&quot;&gt;
          &lt;StackPanel x:Name=&quot;Launch&quot; Orientation=&quot;Horizontal&quot; Visibility=&quot;Collapsed&quot;&gt;
              &lt;!-- Children here --&gt;
          &lt;/StackPanel&gt;
          &lt;ToggleButton x:Name=&quot;ToggleLaunch&quot; IsChecked=&quot;False&quot; Content=&quot;Launch&quot;/&gt;
      &lt;/StackPanel&gt;
  &lt;/UserControl&gt;
  </code></pre>
  <p>I've been trying to use a DataTrigger to make the 'Launch' StackPanel become visible when the ToggleButton is checked, and remain collapsed otherwise.  However, at runtime I get an error stating &quot;Failed object initialization (ISupportInitialize.EndInit). Triggers collection members must be of type EventTrigger&quot;.  I've tried adding it to the trigger collection of the UserControl and StackPanel with no success.  My trigger XAML looks like the following:</p>
  <pre><code>&lt;DataTrigger Binding=&quot;{Binding ElementName=ToggleLaunch, Path=IsChecked}&quot; Value=&quot;True&quot;&gt;
      &lt;Setter TargetName=&quot;Launch&quot; Property=&quot;UIElement.Visibility&quot; Value=&quot;Visible&quot;/&gt;
  &lt;/DataTrigger&gt;
  </code></pre>