Power manager turn off the screen

Hello, I have a problem with the power manager. With both power adapter and battery, I have it set to never turn off the screen. Still it does. I also have the screensaver disabled. What I can do?
Thank you.

You can install Caffeine. It's an app that lets you keep the screen on. It's described in the Productivity Applications section of the Ubuntu MATE guide.

Thank you. I will try it. Although I am a little concerned that the real power manager is not working.