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