How to set default zoom-in factor on chart load

Dear all,

I am trying to load my chart with a default zoom factor value. For that I have follow and modify the exemple shown by using key stroke.

My modifiier class is defined as below :

 public class SimpleZoomInOutModifier : ChartModifierBase
{
    public static readonly DependencyProperty ZoomFractionProperty 
        = DependencyProperty.Register("ZoomFraction", typeof(double), typeof(SimpleZoomInOutModifier), new PropertyMetadata(0.1));

    public double ZoomFraction
    {
        get { return (double)GetValue(ZoomFractionProperty); }
        set { SetValue(ZoomFractionProperty, value); }
    }

    void SciChart_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        double factor = 0;

        if (e.Key == Key.Up)
        {
            // On CTRL+, Zoom In
            factor = -ZoomFraction;
        }
        if (e.Key == Key.Down)
        {
            // On CTRL-, Zoom Out
            factor = ZoomFraction;
        }

        using (ParentSurface.SuspendUpdates())
        {
            // Zoom the XAxis by the required factor
            XAxis.ZoomBy(factor, factor, TimeSpan.FromMilliseconds(500));

            // Zoom the YAxis by the required factor
            YAxis.ZoomBy(factor, factor, TimeSpan.FromMilliseconds(500));

            // Note.. can be extended for multiple YAxis XAxis, just iterate over all axes on the parent surface
        }
    }

    public override void OnAttached()
    {
        base.OnAttached();
        var scichart = ((SciChartSurface)ParentSurface);

        var mainWindow = FindLogicalParent<UserControl>(scichart);

        mainWindow.PreviewKeyDown -= SciChart_PreviewKeyDown;
        mainWindow.PreviewKeyDown += SciChart_PreviewKeyDown;
        mainWindow.Loaded += SciChart_Loaded; 
    }

    private void SciChart_Loaded(object sender, RoutedEventArgs e)
    {
        double factor = 0;
        // On CTRL+, Zoom In
        factor = -ZoomFraction;

        using (ParentSurface.SuspendUpdates())
        {
            // Zoom the XAxis by the required factor
            XAxis.ZoomBy(factor, factor, TimeSpan.FromMilliseconds(500));

            // Zoom the YAxis by the required factor
            YAxis.ZoomBy(factor, factor, TimeSpan.FromMilliseconds(500));

            // Note.. can be extended for multiple YAxis XAxis, just iterate over all axes on the parent surface
        }
    }

From the code above, the zoom in by using Up and Down keys is working perfectly well but when I try to force the zoom in inside the chart_loaded event, nothing happen.

Any idea what I am doing wrong ?

regards