Bonjour,
A mettre dans le module de la feuille et supprimer la MFC :
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column <> 3 Then Exit Sub
If Target.Count > 1 Then Exit Sub
Application.EnableEvents = False
If Target.Value = "" Then
Target.Offset(, -1).Value = "A voir"
Target.Offset(, -1).Interior.Color = 49407
Else
Target.Offset(, -1).Value = "OK"
Target.Offset(, -1).Interior.Color = 16777215
End If
Application.EnableEvents = True
End Sub