Private Function TimeDiff(ByVal Time1 As String, ByVal Time2 As String) As _
  String
        Dim lngMin As Long
        Dim lngStd As Long
        Dim sTime1 As String
        Dim sTime2 As String
 
        sTime1 = DateTimePicker1.Value
        sTime2 = DateTimePicker2.Value
 
        ' Zeitdifferen lässt sich nur berechnen, wenn man
        ' auch ein gültiges Datum mit angibt
        Dim sDate1 As String
        Dim sDate2 As String
 
        sDate1 = CDate(Format$(Now, "m-d-yy"))
 
        ' Wenn sTime2 < sTime1
        sDate2 = DateAdd("d", IIf(sTime2 < sTime1, 1, 0), sDate1)
 
        ' Zeit-Differenz in Minuten
        lngMin = DateDiff("n", CDate(sDate1 & " " & sTime1), _
          CDate(sDate2 & " " & sTime2))
 
        ' Und jetzt ins Format hh:nn umwandeln
        lngStd = Int(lngMin / 60)
        lngMin = lngMin - (lngStd * 60)
 
        Dim Uhrzeit As String
        Uhrzeit = "Zeit-Differenz: " & _
          Format$(lngStd, "00") & ":" & Format$(lngMin, "00")
        Label5.Text = Uhrzeit
 
    End Function

Private Function TimeDiff(ByVal datTime1 As Date, ByVal datTime2 As Date) As _
  String
Dim lngMin As Long
Dim lngStd As Long
 
If datTime2 < datTime1 Then datTime2 = DateAdd("d", 1, datTime2)
 
lngMin = DateDiff("n", datTime1, datTime2)
lngStd = Int(lngMin / 60)
lngMin = lngMin Mod 60
 
TimeDiff = "Zeit-Differenz: " & Format$(lngStd, "00") & ":" & Format$(lngMin, _
  "00")
End Function
 
 
Private Sub Command1_Click()
Label5.Caption = TimeDiff(DateTimePicker1.Value, DateTimePicker2.Value)
End Sub