If you look at the default pay lines for the employee I suspect you will have 56 hours of ordinary time. If you're using timesheets you should set the default hours to 0. If there is no ordinary time in the timesheets then the default pay line will be inserted into the pay itself. This is so that companies can use timesheets for leave recording only and have the hours automatically inserted into the pay. So set the hours to zero in the default pay and you'll be right.