The guide is empty, or a group looks empty

An empty guide

Providers differ in how much schedule information they publish, and some publish none for certain channels. Pull down to refresh on the channel list first. If a channel still shows nothing where others are full, your provider has no schedule for it.

A group with nothing in it

The app lists every group your provider reports, and fetches a group's contents when you open it. So a group that looks empty at first glance usually fills in a moment later.

If it is still empty after that, your subscription genuinely does not include those channels. Ask your provider to add the package.

A group with a padlock

That is the parental lock, which is always on. If nobody has set a PIN on this device, the code is 0000 unless your provider has put a different one on your line. The parental PIN and adult content explains all three codes and how to set your own.