blocage de saisie des occurences serie de chiffre dans une ligne

Private Sub Worksheet_Change(ByVal  Target As Range)
Dim L As Long
If Target.Column > 1 Or Target.Count <> 1 Then Exit Sub
If Target.Value = "" Then Exit Sub
L = WorksheetFunction.CountIf(Me.[A:A], Target.Value)
If L < 2 Then Exit Sub
MsgBox """" & Target.Value & """ existe déjà.", vbCritical, "Saisie d'un doublon"
Target.ClearContents: Target.Select
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
Dim L As Long
If Target.Row > 1 Or Target.Count <> 1 Then Exit Sub
If Target.Value = "" Then Exit Sub
L = WorksheetFunction.CountIf(Me.[1:1], Target.Value)
If L < 2 Then Exit Sub
MsgBox """" & Target.Value & """ existe déjà.", vbCritical, "Saisie d'un doublon"
Target.ClearContents: Target.Select
End Sub