------------- XAML -----------------

<s:RolloverModifier IsEnabled="{Binding TooltipChecked, Mode=TwoWay}" ShowTooltipOn="Always" SourceMode="AllSeries" SeriesData="{Binding DistanceSeriesData, Mode=TwoWay}" />
<s:VerticalSliceModifier VerticalLines="{Binding DistanceVerticalLines, Mode=TwoWay}"   IsEnabled="True" />

------------- View Model ---------------

	ChartDataObject distanceSeriesData = new ChartDataObject(new ObservableCollection<SeriesInfo>());
        ChartDataObject DistanceSeriesData
        {
            get { return distanceSeriesData; }
            set { distanceSeriesData = value; OnPropertyChanged(nameof(DistanceSeriesData)); }
        }

        VerticalLineAnnotationCollection distanceVerticalLines = new VerticalLineAnnotationCollection();
        VerticalLineAnnotationCollection DistanceVerticalLines
        {
            get { return distanceVerticalLines; }
            set { distanceVerticalLines = value; OnPropertyChanged(nameof(DistanceVerticalLines)); }
        }

        public ICommand DistanceMouseLeftButtonUpCommand
        {
            get
            {
                return new DelegateCommand<object>(_ =>
                {
                    if (TooltipChecked == true)
                    {
                        if (DistanceSeriesData != null)
                        {
                            if (DistanceSeriesData.SeriesInfo.Count > 0) //!!!! SERIESINFO.COUNT always ZERO
                            {
                                IComparable xPoint = DistanceSeriesData.SeriesInfo[0].FormattedXValue;
                                DistanceVerticalLines?.Add(new VerticalLineAnnotation()
                                {
                                    X1 = 5,
                                    IsEditable = true,
                                    LabelPlacement = LabelPlacement.Axis,
                                    ShowLabel = true,
                                    LabelTextFormatting = "0.0000",

                                });
                            }
                        }
                    }
                });
            }
        }