Private Function TimeAdd(ByVal Time1 As String, ByVal Time2 As String) As String
Dim lStd As Long, lMin As Long, lSec As Long
Dim lTmpTime1 As Long
 
'erste zeit in millisekunden umrechnen
lStd = Mid(Time1, 1, 2)
lMin = Mid(Time1, 4, 2)
lSec = Mid(Time1, 7, 2)
 
If lMin + Int(Mid(Time2, 4, 2)) <= 60 Then
  'Eine stunde kürzen wenn beide minuten zahlen unter 60 sind
  lStd = lStd - 1
End If
 
lStd = ((lStd * 60) * 60) * 1000
lMin = (lMin * 60) * 1000
lSec = lSec * 1000
lTmpTime1 = lStd + lMin + lSec
 
'Zweite zeit in millisekunden umrechnen
lStd = Mid(Time2, 1, 2)
lMin = Mid(Time2, 4, 2)
lSec = Mid(Time2, 7, 2)
 
lStd = ((lStd * 60) * 60) * 1000
lMin = (lMin * 60) * 1000
lSec = lSec * 1000
 
TimeAdd = TimeFormat(lTmpTime1 + lStd + lMin + lSec)
End Function