expression.Separator
expression Required. An expression that returns one of the objects in the Applies To list.
Remarks
The chart must first be active before you can access the data labels programmatically; otherwise a run-time error occurs.
Example
This example sets the data label separator for the first series on the first chart to a semicolon. This example assumes a chart exists on the active worksheet.
Sub ChangeSeparator()
ActiveSheet.ChartObjects(1).Activate
ActiveChart.SeriesCollection(1) _
.DataLabels.Separator = ";"
End Sub