ASP.NET Chart Series Grouping Issue

[pickles]

According to msdn I should be able to group data in my Chart control's Data Source in the code behind using the GroupByAxisLabel method in the DataManipulator class. I just can't seem to get it to actually work. What am I missing? \[code\]<asp:Chart ID="OpenVsClosed" runat="server" DataSourceID="ObjectDataSource1" BackColor="Gray" BackGradientStyle="DiagonalLeft"> <Series> <asp:Series Name="Series1" XValueMember="Site" YValueMembers="CallNumber" Color="Silver"></asp:Series> </Series> <ChartAreas> <asp:ChartArea Name="ChartArea1"> <Area3DStyle Enable3D="True" /> </asp:ChartArea> </ChartAreas> <Titles> <asp:Title Name="Open v Closed" Text="Test Data"></asp:Title> </Titles></asp:Chart>protected void Page_Load(object sender, EventArgs e) { OpenVsClosed.DataManipulator.GroupByAxisLabel("COUNT", "Series1"); }\[/code\]The included chart has one series with an X axis corresponding to a string value representing the site name of the service call. The Y axis is set to another string value representing the call number itself. I want to group by site with a count of unique call numbers at each site.