Binding Annotations to an AnnotationsCollection

Hi,

I have a scichart surface defined in xaml like this,

<local:SciChartSurface x:Name="_ChartSurface"  Annotations="{Binding ChartAnnotations}">

        </local:SciChartSurface>

In the code behind I have ChartAnnotations defined as,

 public const string ChartAnnotationsPropertyName = "ChartAnnotations";
        private AnnotationCollection _ChartAnnotations = new AnnotationCollection();
        public AnnotationCollection ChartAnnotations
        {
            get { return _ChartAnnotations; }
            set
            {
                if (_ChartAnnotations == value)
                    return;

                _ChartAnnotations = value;
                RaisePropertyChanged(ChartAnnotationsPropertyName);
            }
        }

 public ViewModelExample()
{  
  ChartAnnotations.CollectionChanged += ChartAnnotations_CollectionChanged;    
}

 void ChartAnnotations_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
            RaisePropertyChanged(ChartAnnotationsPropertyName);          
        }

Than in the code behind, I just initialize and add some annotations to the ChartAnnotations collection to populate my chart. The problem is that my Annotations property on the scichart surface is still null, and the RaisePropertyChanged() is not affecting the Bindings at all. I’m certain that the DataContext is set right as other stuff in the graph works fine. I works when I explicitly set the surface’s Annotations property with my ChartAnnotations collection, but obviously this is less than ideal.

Is there an additional step that I’m missing here?

Thanks