All DateTimePickers on the form some time show time in incorrect format. That depends on current regional settings. If regional settings use a 24 hour clock form translates the time into 12 hour format without AM/PM notations. And it is impossible to set a time for PM preriod.
https://taskscheduler.codeplex.com/discussions/659231
Comments: Fixed in 2.5.22
https://taskscheduler.codeplex.com/discussions/659231
Comments: Fixed in 2.5.22