SciChartSurface Mouse Down event

Hi there

I got 2(or more) charts, and want to make line annotation on both
So i create 2 or more annotationCreationModifier, and want to releaseMouseCapture after the first point of line is placed at any of charts, for this im using SciChartSurface.MouseDown event

    List<AnnotationCreationModifier> AnnotationCreatorsList = new List<AnnotationCreationModifier>();

    public void LineAnotationCreaterModifier() 
    {
        AnnotationCreatorsList.Clear();

        AnnotationCreater = new AnnotationCreationModifier() { AnnotationType = typeof(LineAnnotation) };
        AnnotationCreater.AnnotationCreated += new EventHandler(AnnotationCreater_LineAnnotationCreated);
        PriceChart.ChartControl.ChartModifier = AnnotationCreater;
        PriceChart.ChartControl.MouseDown += new MouseButtonEventHandler(ChartControl_MouseDown);


        AnnotationCreatorsList.Add(AnnotationCreater);

        foreach (ChartArea a in SecondaryCharts)
        {
            AnnotationCreater = new AnnotationCreationModifier() { AnnotationType = typeof(LineAnnotation) };
            AnnotationCreater.AnnotationCreated += new EventHandler(AnnotationCreater_LineAnnotationCreated);
            a.ChartControl.MouseDown += new MouseButtonEventHandler(ChartControl_MouseDown);
            a.ChartControl.ChartModifier = AnnotationCreater;
            AnnotationCreatorsList.Add(AnnotationCreater);
        }
    }


    void ChartControl_MouseDown(object sender, MouseButtonEventArgs e)
    {
        PriceChart.ChartControl.MouseDown -= new MouseButtonEventHandler(ChartControl_MouseDown);
        foreach (ChartArea a in SecondaryCharts)
        {
            a.ChartControl.MouseDown -= new MouseButtonEventHandler(ChartControl_MouseDown);
        }

        if (e.ChangedButton == MouseButton.Left)
        {
            var area = sender as SciChartSurface;

            foreach (var ancr in AnnotationCreatorsList)
            {
                if (ancr.ParentSurface == area) { }
                else { ancr.ReleaseMouseCapture(); }
            }
        }
    }

But i cant understand when mousedown event executes
It allways executes when i click on a board
And sometimes executes at the second click (after first click, when the first point is placed)

I made video, and will post it

Here is link for video: