title: Multibinding generates "Cannot set MultiBinding because MultiValueConverter must be specified"
body: <p>I have a button with binding which works fine, see below:</p>
  
  <pre><code>&lt;Button x:Name="licenceFilterSet" Content="Search" Command="{Binding searchCommand}" CommandParameter="{Binding Path=Text, ElementName=licenseTextBox}" /&gt;
  </code></pre>
  
  <p>Now I have realized that I need yet another piece of information, so I need to send the value of a <code>check-box</code> as well.
  I modified the VM like this:</p>
  
  <pre><code>&lt;Button x:Name="licenceFilterSet" Content="Search" Command="{Binding licenseSearchCommand}"&gt;
      &lt;Button.CommandParameter&gt;
          &lt;MultiBinding Converter="{StaticResource searchFilterConverter}"&gt;
              &lt;Binding Path="Text" ElementName="licenseTextBox" /&gt;
              &lt;Binding Path="IsEnabled" ElementName="regularExpressionCheckBox" /&gt;
          &lt;/MultiBinding&gt;
      &lt;/Button.CommandParameter&gt;
  &lt;/Button&gt;
  </code></pre>
  
  <p>Below is my multi-converter:</p>
  
  <pre><code>/// &lt;summary&gt;
  /// Converter Used for combining license search textbox and checkbox
  /// &lt;/summary&gt;
  public class SearchFilterConverter : IMultiValueConverter
  {
      public object Convert(object[] values)
      {
          return new Tuple&lt;String, bool&gt;((String)values[0], (bool)values[1]);
      }
  }
  </code></pre>
  
  <p>What am I doing wrong. I am getting the following error, (which is pointing to my MultiBinding-tag in XAML):</p>
  
  <pre><code>Cannot set MultiBinding because MultiValueConverter must be specified.
  </code></pre>