my English is not so good so I apologize in advance.  

I tried something with the object `Chart` in a `WindowsFormsApplication`.  

I built a program that looks like this:
[![enter image description here](https://i.stack.imgur.com/noCNu.png)](https://i.stack.imgur.com/noCNu.png)  

And that is the code:

```
private void Form1_Load(object sender, EventArgs e)
    {
        chart1.Dock = DockStyle.Fill;
        chart1.Series.Clear();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        chart1.Series.Clear();
        chart1.Series.Add("button1 Series");

        for (int i = 1; i <= 100; i++)
            chart1.Series[0].Points.AddXY(i, i * 2);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        chart1.Series.Clear();
        chart1.Series.Add("button2 Series");

        for (int i = 1; i <= 100; i++)
            chart1.Series[0].Points.AddXY(i, i * 4);
    }

```

When I click the first button (`button1`), the graph is displayed as I want:
[![button1](https://i.stack.imgur.com/WADvH.png)](https://i.stack.imgur.com/WADvH.png)  

But if after that I hit the second button (`button2`), points on the y-axis escape out:[![button2](https://i.stack.imgur.com/zfg3v.png)](https://i.stack.imgur.com/zfg3v.png)

The maximum of the y-axis (250) stay the same instead change to bigger.  

How can I fix my program so that the graph will not get out of the area?  

Thanks, and sorry again for my English