Makro veränderbar?

Private Sub TextBox14_Exit(ByVal Cancel As MSForms.ReturnBoolean)
Dim myH As Long, myM As Long, myS As Long
Select Case Len(TextBox14)
Case 4
Select Case Left(TextBox14, 2)
Case 0 To 24
myH = Left(TextBox14, 2)
Case Else
MsgBox "Falsche Stundenzeit", vbOKOnly + vbCritical, "Fehler"
Cancel = True
Exit Sub
End Select
Select Case Right(TextBox14, 2)
Case 0 To 60
myM = Right(TextBox14, 2)
Case Else
MsgBox "Falsche Minutenangabe", vbOKOnly + vbCritical, "Fehler"
Cancel = True
Exit Sub
End Select
TextBox14 = Format(myH & ":" & myM, "hh:mm:ss")
Case 6
Select Case Left(TextBox14, 2)
Case 0 To 24
myH = Left(TextBox14, 2)
Case Else
MsgBox "Falsche Stundenzeit", vbOKOnly + vbCritical, "Fehler"
Cancel = True
Exit Sub
End Select
Select Case Mid(TextBox14, 3, 2)
Case 0 To 60
myM = Mid(TextBox14, 3, 2)
Case Else
MsgBox "Falsche Minutenangabe", vbOKOnly + vbCritical, "Fehler"
Cancel = True
Exit Sub
End Select
Select Case Right(TextBox14, 2)
Case 0 To 60
myS = Right(TextBox14, 2)
Case Else
MsgBox "Falsche Sekundenangabe", vbOKOnly + vbCritical, "Fehler"
Cancel = True
Exit Sub
End Select
TextBox14 = Format(myH & ":" & myM & ":" & myS, "hh:mm:ss")
Case Else
MsgBox "Eingabe entspricht nicht der Erwartung und kann nicht konvertiert werden",  _
vbOKOnly + vbCritical, "Fehler"
Cancel = True
TextBox14 = ""
End Select
End Sub