ZedGraph初学问题

[qq_31812171]

刚运行的结果如图：

滚动鼠标后的结果如图：

代码：
using ZedGraph;
...
private void Form1_Load(object sender, EventArgs e)
{
GraphPane myPane = zg.GraphPane;
//标题
myPane.Title.Text = "Tutorial Initial Sample";
myPane.XAxis.Title.Text = "XAxis.Title";
myPane.YAxis.Title.Text = "YAxis.Title";
myPane.Y2Axis.Title.Text = "Y2Axis.Title";
//坐标
PointPairList list = new PointPairList();
list.Add(100, 1);
list.Add(200, 4);
list.Add(300, 6);
list.Add(400, 8);
list.Add(500, 10);
list.Add(600, 20);

//线条样式
LineItem myCurve = myPane.AddCurve("Alpha",
list, Color.Red, SymbolType.Diamond);

//辅助虚线
myPane.YAxis.MajorGrid.IsVisible = true;
myPane.XAxis.MajorGrid.IsVisible = true;

////刻度值
myPane.YAxis.Scale.Min = 0;
myPane.YAxis.Scale.Max = 30;
myPane.XAxis.Scale.Min = 0;
myPane.XAxis.Scale.Max = 600;

zg.Size = new Size(500, 300);
this.Controls.Add(zg);
}
怎样才可以一运行就是图二？