MSChart cheat sheet

Microsoft bought Dundas charts.  Sometimes it helps to google that tool as well.  Better documented.
Dundas Documentation

Line graphs are not fond of nulls, seems to mess up results

Formatting
chart.Series[name].Label = "#VALY{C0}";  //will give you the value of Y formatting with currency

chart.ChartAreas[0].AxisY.LabelStyle.Format = "{C0}";  //format the labels of the Y axis with currency