title: WPF. Must have non-null value for 'Property' for multitrigger condition
body: <p>Have multitrigger, one of the conditions is not null, so if StowedAssetDetailedThumbnailViewModel != null then set template</p>
  
  <pre><code>&lt;Style.Triggers&gt;
      &lt;MultiTrigger&gt;
          &lt;MultiTrigger.Conditions&gt;
              &lt;Condition Property="IsSelected" Value="true" /&gt;
              &lt;Condition Binding="{Binding Path=StowedAssetDetailedThumbnailViewModel,
                                           Converter={StaticResource isNull}}"
                         Value="False"/&gt;
          &lt;/MultiTrigger.Conditions&gt;
          &lt;Setter Property="Template" Value="{StaticResource SelectedTemplate}" /&gt;
      &lt;/MultiTrigger&gt;
  &lt;/Style.Triggers&gt;
  </code></pre>
  
  <p>Using simple converter:</p>
  
  <pre><code>return isNull == null;
  </code></pre>
  
  <p>the error is 
  <strong>Must have non-null value for Property</strong></p>
  
  <p>UPDATE:
  Thanks, the final solution is </p>
  
  <pre><code>&lt;Style.Triggers&gt;
      &lt;MultiDataTrigger&gt;
          &lt;MultiDataTrigger.Conditions&gt;
              &lt;Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}"
                         Value="true" /&gt;
              &lt;Condition Binding="{Binding Path=StowedAssetDetailedThumbnailViewModel,
                                   Converter={StaticResource isNull}}"
                                   Value="false"/&gt;
          &lt;/MultiDataTrigger.Conditions&gt;
  
          &lt;Setter Property="Template" Value="{StaticResource SelectedTemplate}" /&gt;
      &lt;/MultiDataTrigger&gt;
  &lt;/Style.Triggers&gt;
  </code></pre>