Before using the ShowValueLabels property, make sure the DevExpress.XtraCharts.ChartControl.CrosshairEnabled property is set to true.
The following table shows this property in action.
ShowValueLabels=True |
ShowValueLabels=False |
 |
 |
Note that the MarkerVisibility property for a particular series (e.g. LineSeriesView.MarkerVisibility) is set to false by default to support series point highlighting on a Diagram (in XtraCharts for WinForms only).
To learn more about the crosshair cursor, see the Crosshair Cursor topic.