Private Sub Text1_Validate(Index As Integer, Cancel As Boolean)
  ' Prüfung
  With Text1(Index)
    Select Case Index
      Case 0
        If Left$(.Text, 1) <> "3" Then Cancel = True
      Case 1
        If Left$(.Text, 1) <> "4" Then Cancel = True
      Case 2
        If Left$(.Text, 1) <> "5" Then Cancel = True
      Case 3
        If Left$(.Text, 1) <> "6" Then Cancel = True
    End Select
  End With
End Sub