Parental Controls Time Limit

I have set up my HDDVR Receiver - HR22-100 - and I have set my Parental Controls to limit the viewing hours from 2:30 PM - viewable for 18 hours - making the receiver inaccessible between the hours of 8:30AM and 2:30PM - when we are homeschooling our children.

Every couple of days, I need to reset this, because the viewable hours resets back from 18 hours to 9 hours viewable.

Why does this keep resetting - this is aggravating as I have to unlock it for the kids to watch TV before school starts - when they are allowed to....