Problème d'insertion des données sources pour graphique courbes.

Option Explicit
Sub test()
Dim  c As Chart, s As Series, r As Range
Set c = Feuil1.ChartObjects(1).Chart
For Each s In c.SeriesCollection
    s.Delete
Next s
For Each r In Range("D1:" & Range("IV1").End(xlToLeft).Address)
    Set s = c.SeriesCollection.NewSeries
    With s
        .Name = r
        .Values = Feuil1.Range("C8:C88")
        .XValues = Feuil1.Cells(8, r.Column).Resize(81, 1)
    End With
Next r
End Sub

Option Explicit
Sub test()
Dim ws As Worksheet, c As Chart, s As Series, r As Range
Set ws = Worksheets("Tableaux horaires impairs")
Set c = ws.ChartObjects(1).Chart
For Each s In c.SeriesCollection
    s.Delete
Next s
For Each r In ws.Range("D1:" & ws.Range("IV1").End(xlToLeft).Address)
    Set s = c.SeriesCollection.NewSeries
    With s
        .Name = r
        .Values = ws.Range("C8:C88")
        .XValues = ws.Cells(8, r.Column).Resize(81, 1)
    End With
Next r
With c.Axes(xlCategory)
    .MinimumScale = 0
    .MaximumScale = Application.Max(ws.Range("D8").Resize(81, ws.Range("IV1").End(xlToLeft).Column - 3))
End With
End Sub