Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("c6:c18", "g18:h18")) Is Nothing Then
If Target > [I3] Then
MsgBox "Attention valeur trop grande !" & vbCr & _
"Vous ne devez pas d?passer " & [I3], vbExclamation + vbRetryCancel, "ANNULATION"
Target.Value = "" 'on efface
End If
End If
End Sub