VB Code:
Private Function TimeDiff(strTimeIn As String, strTimeOut As String)
Dim hour As Long, min As Long, sec As Long
Dim time1 As Date, time2 As Date
time1 = CDate(strTimeIn)
time2 = CDate(strTimeOut)
sec = DateDiff("s", time1, time2)
Do While sec < 0 Then
time2 = time2 + 1 'add 1 day
sec = DateDiff("s", time1, time2)
Loop
hour = Int(sec / 3600)
sec = sec - (hour * 3600)
min = Int(sec / 60)
sec = sec - (min * 60)
TimeDiff = Format(hour, "00") & ":" & Format(min, "00") & ":" & Format(sec, "00")
End Function