如何在堆叠的条形图中添加标记或注释

Question

我创建了一个带有单个水平条的堆积条形图。 我想在每两个堆栈连接的位置上方显示一个注释或标记，如图所示。 我的条形图显示正常，但无法显示注释。 L1，L2，L3和L4的值已在代码中提前设置

Dim BeamSeries1, BeamSeries2, BeamSeries3, BeamSeries4, BeamSeries5 As New Series

    BeamSeries1.ChartType = SeriesChartType.StackedBar
    BeamSeries2.ChartType = SeriesChartType.StackedBar
    BeamSeries3.ChartType = SeriesChartType.StackedBar
    BeamSeries4.ChartType = SeriesChartType.StackedBar



        If L1 > 0 Then
            BeamSeries1.Points.AddY(L1)
            cht_Beam.Series.Add(BeamSeries1)
        End If
        If L2 > 0 Then
            BeamSeries2.Points.AddY(L2 - L1)
            cht_Beam.Series.Add(BeamSeries2)
        End If
        If L3 > 0 Then
            BeamSeries3.Points.AddY(L3 - L2)
            cht_Beam.Series.Add(BeamSeries3)
        End If
        If L4 > 0 Then
            BeamSeries4.Points.AddY(L4 - L3)
            cht_Beam.Series.Add(BeamSeries4)
        End If

    End With

    'annotate
    Dim AA As New ArrowAnnotation
    AA.LineWidth = 2
    AA.AnchorDataPoint = BeamSeries1.Points.First

    AA.Visible = True
    AA.ArrowStyle = ArrowStyle.Simple
    cht_Beam.Annotations.Add(AA)


    'marker
    BeamSeries1.MarkerStyle = MarkerStyle.Triangle
    BeamSeries1.Points.First.MarkerStyle = MarkerStyle.Triangle

在上面的代码中，我尝试向图表的第一点添加箭头注释和标记，但均未显示。我既不希望注释也不需要标记。