Why is the schedule selector empty?

The selector lists the schedules in your account. If it's empty, there's no schedule to send yet.

What to check

1. Open Schedules and confirm a schedule exists. If not, create one.
2. Open the schedule and make sure it has at least one playlist time slot. A schedule with no slots has nothing to show.
3. Check the playlist in that slot has content — see Create a playlist.
4. Go back to Push to Devices and choose the schedule under What to send.