HI,
Wire up the XamDataChart's SeriesMouseLeftButtondown event.
Look at the event args e.Item, this will have the value of the bar or column.
Here is a help link: http://help.infragistics.com/NetAdvantage/WPF/2013.1/CLR4.0/?page=InfragisticsWPF4.Controls.Charts.XamDataChart.v13.1~Infragistics.Controls.SeriesViewer~SeriesMouseLeftButtonDown_EV.html
Sincerely, Matt Developer Support Engineer