Ereignis: Zahlen in vorgegebene Zeichenkette

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If Target.Count > 1 Then Exit Sub
If Intersect(Target, [a:a]) Is Nothing Then Exit Sub
On Error GoTo errorhandler
Application.EnableEvents = False
'Target = CStr(Format(Target, "000/00/0"))
Select Case Len(Target.Value)
Case 7
'z.B.1234567=1234/56/7
'Target =?
Case 6
'z.B.123456=123/45/6
Case 5
'z.B.12345=12/34/5
'Target =?
Case 4
'z.B.1234=1/23/4
'Target =?
Case Else:
Target.ClearContents
End Select
Application.EnableEvents = True
Exit Sub
errorhandler:
Target.ClearContents
Application.EnableEvents = True
End Sub