求助：c#用Chart控件编写Realtime Curve时，遇到的问题。。。（求大神帮忙看哪儿出问题了））

Question

 protected  void timer1_Tick(object sender, EventArgs e)
        {
            Random random = new Random();            foreach (Series series in Chart1.Series)
            {
                double xLastValue = series.Points[series.Points.Count - 1].XValue + 1;
                double yLastValue = series.Points[series.Points.Count - 1].YValues[0];                for (int i = 0; i < 5; i++)
                {
                    yLastValue += random.Next(-3, 4);
                    if (yLastValue >= 100.0)
                    {
                        yLastValue -= 25.0;
                    }
                    if (yLastValue <= 10.0)
                    {
                        yLastValue += 25.0;
                    }
                    series.Points.AddXY(xLastValue++, yLastValue);
                    
                }
                Chart1.Series.Add(series); 
            }
                        while (Chart1.Series[0].Points.Count > 4)            {
                foreach (Series series in Chart1.Series)
                {
                    series.Points.RemoveAt(0);
                    Chart1.Series.Add(series); 
                }
            }            double axisMinimum = this.Chart1.Series[0].Points[0].XValue;
            this.Chart1.ChartAreas[0].AxisX.Minimum = axisMinimum;
            this.Chart1.ChartAreas[0].AxisX.Maximum = axisMinimum + 100;
       
        } 初学c#，调用书上的一个例子，可是结果出不来？另个一问题是红色标注有错，提示“索引超出范围。必须为非负值并小于集合大小。
参数名: index”  还请各位多多指教！灰常感谢！C#Chart控件