title: Cannot find source for binding with reference 'RelativeSource FindAncestor'
body: <p>I get this error:</p>
  <pre><code>Cannot find source for binding with reference 'RelativeSource FindAncestor,
  AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1''
  </code></pre>
  <p>On this Binding:</p>
  <pre><code>&lt;DataGridTemplateColumn Visibility=&quot;{Binding DataContext.IsVisible,
       RelativeSource={RelativeSource AncestorType={x:Type UserControl}},
       Converter={StaticResource BooleanToVisibilityConverter}}&quot;&gt;
  </code></pre>
  <p>The <code>ViewModel</code> is sitting as <code>DataContext</code> in <code>UserControl</code>. The <code>DataContext</code> of the <code>DataGrid</code> (sitting in <code>UserControl</code>) is property within the <code>ViewModel</code>, in <code>ViewModel</code> I have a variable that says whether to show a certain line or not, its binding fails, why?</p>
  <p>Here my property :</p>
  <pre><code>private bool _isVisible=false;
  public bool IsVisible
  {
      get { return _isVisible; }
      set
      {
          _isVisible= value;
          NotifyPropertyChanged(&quot;IsVisible&quot;);
      }
  }
  </code></pre>
  <p>When it comes to the function: <code>NotifyPropertyChanged</code> the <code>PropertyChanged</code> event null - mean he failed to register for the binding.</p>
  <p>It should be noted that I have more bindings to <code>ViewModel</code> in such a way that works, here is an example:</p>
  <pre><code>Command=&quot;{Binding DataContext.Cmd,
  RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}&quot; 
  </code></pre>