C#用Chart 的ScrollBar问题

求助！！！我的程序是关于串口通信收集陀螺仪的数据的，其中将采集到的数据通过Chart来绘图。但是用ScrollBar的滚动条时，一按想拉回去看原来画的图滚动条就会消失，这是什么问题

            for (int num = 0; num < 3; num++)
            {
                this.chart1.ChartAreas[num].AxisX.Minimum = 0;
                this.chart1.ChartAreas[num].AxisX.Maximum = w;
                this.chart1.ChartAreas[num].AxisX.ScrollBar.Enabled = true;
                this.chart1.ChartAreas[num].AxisX.ScrollBar.IsPositionedInside = true;
                this.chart1.ChartAreas[num].AxisX.ScaleView.Size = w;
                this.chart1.ChartAreas[num].AxisX.IsStartedFromZero = true;
                this.chart1.ChartAreas[num].AxisX.Interval = w / 10;
                this.chart1.ChartAreas[num].AxisX.MajorGrid.LineColor = System.Drawing.Color.Silver;
                this.chart1.ChartAreas[num].AxisY.MajorGrid.LineColor = System.Drawing.Color.Silver;

干掉scollbar这种垃圾东西，手动写拖拽代码

            ch_a=chart1.ChartAreas[0];
            ch_a.AxisX.ScrollBar.Enabled = false;
            ch_a.AxisX.ScrollBar.Size = 20;
            ch_a.AxisX.ScaleView.Size = xywidth()[0];
            ch_a.AxisX.ScaleView.MinSize = 1;
            ch_a.AxisY.LabelStyle.Angle = 90;//轴显示角度

把chart放在panel里面，然后鼠标控制左右滑动

        //给garph拖拽
        public int dfg = 0;
        public void grap_move(Panel grap)
        {
            Chart ch = (Chart)grap.Controls["ct1"];
            ch.MouseDown += (object sen, MouseEventArgs ef) =>
            {
                dfg = ef.X;
                grap.Cursor = Cursors.Hand;
            };
            ch.MouseUp += (object sen, MouseEventArgs ef) =>
            {
                if (ef.Button == MouseButtons.Left)
                {
                    if (ch.Series[0].Points.Count > xywidth()[0])
                    {
                        ch.ChartAreas[0].AxisX.ScaleView.Position -= Convert.ToInt32((ef.X - dfg) / 8) + 1;
                        dfg = 0;
                    }
                }
                grap.Cursor = Cursors.Default;
            };
        }