Useless after 12 Hours

For some reason, after calculating a day longer than 12 hours, I get a negative sum. Not sure why but it is making life frustrating.
Also if I could specify specifically when meal penalties kick in that would be cool too. Choosing 30min or 15min is easy but what time is this based off of? 6 hours past call?

CCoolPhotos about Wrap Time - Time Card for Film Crews, v3.0.25