title: Can't call method from CallMethodAction on EventTrigger of custom TextBox
body: <p>Getting error : 'Could not find method named 'LostFocus' on object of type 'MyType' that matches the expected signature.'</p>
  
  <pre><code>&lt;DataGridTemplateColumn MinWidth="80" Width="1.25*" Header="6"&gt;
       &lt;DataGridTemplateColumn.CellTemplate&gt;
           &lt;DataTemplate&gt;
               &lt;customControlls:NumericTextBox x:Name="cc" 
                       Style="{StaticResource NumericTextboxStyle}" 
                       Text="{Binding AccountsReceivable.OverdueAtTheEndOfTheReportingPeriod, UpdateSourceTrigger=LostFocus}"&gt;
                   &lt;interactivity:Interaction.Triggers&gt;
                       &lt;interactivity:EventTrigger EventName="LostFocus" SourceName="cc"&gt;
                          &lt;interactions:CallMethodAction TargetObject="{Binding}" MethodName="LostFocus"/&gt;
                       &lt;/interactivity:EventTrigger&gt;
                   &lt;/interactivity:Interaction.Triggers&gt;
               &lt;/customControlls:NumericTextBox&gt;
           &lt;/DataTemplate&gt;
       &lt;/DataGridTemplateColumn.CellTemplate&gt;
  &lt;/DataGridTemplateColumn&gt;
  </code></pre>
  
  <p>And the method in ViewModel which I'm trying to call. I also tried to remove parameters from method, still same error.</p>
  
  <pre><code>public void LostFocus(object sender, EventArgs e){}
  </code></pre>