ActiveChart.SeriesCollection(1).Select
ActiveChart.SeriesCollection(1).HasErrorBars = True
ActiveChart.SeriesCollection(1).ErrorBars.Select
ActiveChart.SeriesCollection(1).ErrorBar Direction:=xlY, Include:=xlBoth, _
Type:=xlCustom, Amount:="=" & nom & "!R5C2:R5C" & nb_classes + 1, MinusValues:="=" & nom & "!R5C2: R5C" & nb_classes + 1
ActiveChart.SeriesCollection(1).ErrorBars.Select
ActiveChart.PlotArea.Select