datetimedifference - wrong result (no replies)

Hello,

I use this code

Trace(dStartTijd,DateSys()+TimeSys() )
PrikKlok.Werktijd = DateTimeDifference(dStartTijd,DateSys()+TimeSys() )
Hadd(Prikklok)

The trace gives the following result
20170921153600000 2017092115410730

The system stores 51 seconds and not the 5 minutes timedifference.

Am I doing something wrong?

Thanks

Willy Hermans