Polar Point and Polar Line series are not compatible

I am trying to display PolarPoint and PolarLine in same chart. See following code:

C#
private void button1_Click(object sender, EventArgs e)  
{  
    Series s = new Series("Points", ViewType.PolarPoint);  
    s.Points.Add(new SeriesPoint(0, 2));  
    s.Points.Add(new SeriesPoint(90, 5));  
    s.Points.Add(new SeriesPoint(180, 3));  
    s.Points.Add(new SeriesPoint(270, 1));  
    chartControl1.Series.Add(s);  
}  

private void button2_Click(object sender, EventArgs e)  
{  
    Series s = new Series("Line", ViewType.PolarLine);  
    s.Points.Add(new SeriesPoint(0, 8));  
    s.Points.Add(new SeriesPoint(90, 6));  
    s.Points.Add(new SeriesPoint(180, 9));  
    s.Points.Add(new SeriesPoint(270, 7));  
    chartControl1.Series.Add(s);  
}  

But it doesn't work as expected: When I click button1 first the PolarPoint series is added and displayed. But subsequent clicks to button2 have no effect. And vice versa.

The problem can be reproduced with the attached project.