Chart.PlotBy (Excel)
Returns or sets the way columns or rows are used as data series on the chart. Can be one of the following XlRowCol constants: xlColumns or xlRows. Possible return values are xlColumns - Data series is in a row, xlRows - Data series is in a column.
For PivotChart reports, this property is read-only and always returns xlColumns.
ActiveChart.PlotBy = xlColumns