c# – 在mschart中添加数据点时双标签

现在我点击330-340之间的数据点.该图表显示了带有双标签的选定数据点(338.61).如下所示：

以下是调试输出：

以下是chart_mouseclick的以下代码

private void chart1_MouseClick(object sender,MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {               
        double mouse_Xvalue = chart1.ChartAreas[0].AxisX.PixelPositionToValue(e.X);
        double mouse_Yvalue = chart1.ChartAreas[0].AxisY.PixelPositionToValue(e.Y);

        DataPoint Prev_DataPoint = chart1.Series[0].Points.Select(x => x)
            .Where(x => x.XValue >= mouse_Xvalue)
            .DefaultIfEmpty(chart1.Series[0].Points.First()).First();

        DataPoint Next_DataPoint = chart1.Series[0].Points.Select(x => x)
            .Where(x => x.XValue <= mouse_Xvalue)
            .DefaultIfEmpty(chart1.Series[0].Points.Last()).Last();

        DataPoint Add_DataPoint = Math.Abs(Prev_DataPoint.XValue - mouse_Xvalue) < Math.Abs(Next_DataPoint.XValue - mouse_Xvalue) ? Prev_DataPoint : Next_DataPoint;

        int add_data_point_index = chart1.Series[0].Points.IndexOf(Add_DataPoint);

        DataPoint max = Add_DataPoint;
        for (int i = add_data_point_index - 10; i <= add_data_point_index + 10; i++)
        {
            DataPoint dp = chart1.Series[0].Points[i];

            if (dp.YValues[0] > max.YValues[0])
            {
                add_data_point_index = i;
                max = dp;
            }
        }

        chart1.Series[1].Points.Add(max);
        chart1.Series[1].Sort(PointSortOrder.Ascending,"X");

        for (int i = 0; i < chart1.Series[1].Points.Count; i++)
        {
            chart1.Series[1].Points[i].Label = 
            Math.Round(chart1.Series[1].Points[i].XValue,2).ToString();
        }                 
    }
}

代码有什么问题？