There are 2 levels of scheduling- campaign scheduling and signage scheduling. The campaign schedule determines which content is assigned to the zones during a given calendar period.
A signage schedule determines which signs are shown on different days of the week or times of the day.
Try the following steps to troubleshoot scheduling issues:
Has the campaign schedule been set-up correctly for the timing you would like to achieve?
If you're using a signage schedule, has it been set-up correctly for the timing you would like to achieve?
If you're using a signage schedule, has the right schedule definitely been deployed to the right location?
Is the signage changing, but just at the wrong times?
If the signage is changing at the wrong times, and the discrepancy is a whole number of hours, it may be a time zone issue.
The signage device has a time zone setting, which is set to London by default. To amend the device time zone, you can plug a USB mouse into the device and double-right click to access the Android settings. Finally, consider adding a test sign that includes a 'Date and Time' layer. From this you can determine the current time from the device's point of view.