We have the following view:

<UserControl x:Class="DetailedSalesView" ...
  <Grid x:Name="LayoutRoot">
    <toolkit:BusyIndicator x:Name="activityControl"

                                   IsBusy="{Binding IsBusy}"

                                   BusyContent="{Binding}" >

         <Grid>
             The rest of the control
            </Grid>
        </toolkit:BusyIndicator>
    </Grid>
</UserControl>

When this is instantiated normally the busy indicator appears as expected. The view model implements `INotifyPropertyChanged` and has the property `IsBusy` which gets set at the appropriate places.

We are trying to display this same view in a XamDialogWindow and everything is working except for the BusyIndicator.

The code we have is:

    this._eventAggregator = container.Resolve<IEventAggregator>();

Where `container` is an `IUnityContainer`

    var childViewModel = new DetailedSalesVM(dataService, _eventAggregator);
    var childView = new DetailedSalesView(_eventAggregator, childViewModel);

    var window = new XamDialogWindow
    {
        Width = 800,
        Height = 600,
        Content = childView,
        StartupPosition = StartupPosition.Center,
        Header = headerText
    };

    parent.Children.Add(window);

Where `dataService` is a class that implements the RIAServices connection to the database, and `parent` is the `UIElement` we wish to display the dialog window in.

The view populates correctly and the `IsBusy` property on the view model is set as expected, but the `BusyIndicator` just doesn't display.

What are we missing?