aide graphique par macro

Sub CrééGraph()
Dim DLig As Long, Lig As Long
Dim FirstCel As String, LastCel As String
Dim FirstF As String, LastF As String
Dim FirstP As String, LastP As String
Dim VAn As Integer
Dim Zone As String
  VAn = Sheets("Feuil1").TextBox1
  FirstCel = "": LastCel = ""
  An_ok = False
  VAn = Sheets("Feuil1").TextBox1
  For n = 1 To Sheets("Donnée").Range("A65536").End(xlUp).Row
    If Year(Sheets("Donnée").Range("A" & n)) = VAn Then
      An_ok = True
      Exit For
    End If
  Next n
  If An_ok = False Then
    MsgBox ("Cette Année n'existe pas")
    Exit Sub
  End If
  FirstCel = "": LastCel = ""
  With Sheets("Donnée")
    DLig = .Range("A" & Rows.Count).End(xlUp).Row
    ' Trouver la zone de données sources pour le graphique
    For Lig = 1 To DLig + 1
      If Year(.Range("A" & Lig)) = VAn And FirstCel = "" Then
        FirstCel = .Range("A" & Lig).Address(0, 0)
      End If
      If FirstCel <> "" And Year(.Range("A" & Lig)) <> VAn Then
        LastCel = .Range("A" & Lig - 1).Address(0, 0)
        Exit For
      End If
    Next
    FirstF = "F" & Mid(FirstCel, 2)
    LastF = "F" & Mid(LastCel, 2)
    FirstP = "P" & Mid(FirstCel, 2)
    LastP = "P" & Mid(LastCel, 2)
    Zone = FirstCel & ":" & LastCel & "," & FirstF & ":" & LastF & "," & FirstP & ":" & LastP
    Sheets("graph.1").Activate
    Sheets("graph.1").Shapes(1).Select
    ActiveChart.SetSourceData Source:= _
      Sheets("Donnée").Range(Zone), PlotBy:=xlColumns
    Range("A1").Select
  End With
End Sub