Thanks for the reply. I had actually figured it out yesterday and forgot to post. Using the DateTime overload of the Add moethod worked for me.

I am trying to create a line chart with multiple series where all the series may not share the same x-axis values. All series use dates for the labels one of the series may use a different set of date values. For example, the data for the first two series may look like: Label - S1 Value - S2 Value 1...