Private Sub Worksheet_Change(ByVal Target As Range)
Dim Bereich1 As Range
Set Bereich1 = Range("G2:G10")
If Target.Cells.Count > 1 Then Exit Sub
If Target.Value = "" Then Exit Sub
If Intersect(Bereich1, Target) Is Nothing Then Exit Sub
If WorksheetFunction.CountIf(Bereich1, Target.Value) > 1 Then
MsgBox ("Doppelter Eintrag nicht zulässig")
Application.EnableEvents = False
Target.Value = ""
Application.EnableEvents = True
Target.Select
End If
End Sub