title: WPF MultiBinding to Background Property Not Working
body: <p>MultiBinding to Background property does not work. When it is converted, the background simply turns to the system's default color, not what I have set in the MultiValueConverter. Everything else is set up propertly.  What's wrong with my MultiBinding to Background?         </p>
  
  <pre><code>&lt;Style.Triggers&gt;
      &lt;DataTrigger Binding="{Binding Source={StaticResource triggerResource},
                                     Path=MyIsSelected}"         
                   Value="True"&gt;
          &lt;Setter Property="Background"&gt;
              &lt;Setter.Value&gt;
                  &lt;MultiBinding Converter="{StaticResource groupNameToBackgroundConv}"&gt;
                      &lt;Binding Path="Name" /&gt;
                      &lt;Binding Source="{StaticResource selectedGroupName}" Path="Name" /&gt;
                  &lt;/MultiBinding&gt;
              &lt;/Setter.Value&gt;
          &lt;/Setter&gt;
      &lt;/DataTrigger&gt;
  &lt;/Style.Triggers&gt;
  </code></pre>
  
  <p>And my MultiValueConverter is </p>
  
  <pre><code> public class GroupNameToBackgroundConv : IMultiValueConverter
  {
      private const string DEFAULT_COLOR = "#B8CBE9";
      private const string SELECTED_COLOR = "#FFFF00";       
  
      public object Convert(object[] values, Type targetType, object parameter,
          System.Globalization.CultureInfo culture)
      {
          string groupName = values[0] as string;
          string selectedGroupName = values[1] as string;
  
          if (groupName == null)
              return DEFAULT_COLOR;
  
          if (selectedGroupName == null)
              return DEFAULT_COLOR;
  
          if (groupName == selectedGroupName)
          {
              return SELECTED_COLOR;
          }
          else
          {
              return DEFAULT_COLOR;
          }
  
  
      }  // ends method
  
      public object[] ConvertBack(object value, Type[] targetTypes, object parameter,
          System.Globalization.CultureInfo culture)
      {
          throw new NotImplementedException();
      }
  
  } // ends class
  </code></pre>