Sub Pointille()
Dim i As Integer
graph = ActiveSheet.Shapes(1).Name
' MsgBox graph
ActiveSheet.ChartObjects(graph).Activate
B = ActiveChart.SeriesCollection.Count
'MsgBox B
For A = 1 To B
With ActiveChart.SeriesCollection(A)
For i = 1 To 12
With .Points(i)
If Range("b" & i + 1) = "Prévisionnel" Then
.Format.Line.DashStyle = msoLineSysDash
End If
End With
Next
End With
Next A
End Sub