Private Sub Workbook_SheetActivate(ByVal Sh As Object)
 
End Sub

Private Sub Workbook_SheetActivate(ByVal Sh As Object)
      Dim Prop As DocumentProperty
      Dim b As Boolean
 
      If sh.Name <> "Tabelle1" Then Exit Sub 
 
      b = False
      For Each Prop In ActiveWorkbook.CustomDocumentProperties
             If prop.Name = "MyDate" Then b = True : Exit For
      Next
 
      'b = True, der Wert wurde bereits eingestellt, False muß neu erstellt 
      ' werden.
      If b Then
             Sh.Range("A1") = Prop.Value
      Else
             ActiveWorkbook.CustomDocumentProperties.Add "MyDate",False, _
               msoPropertyTypeDate, Now
             Sh.Range("A1").Value = Now
      End If
End Sub