Magic Keyboard backlight not working, no brightness slider

I don't have a brightness slider for the Magic Keyboard in the settings menu. Although the keyboard is connected to my iPad and working, the backlight doesn't turn on automatically in the dark. I added the keyboard brightness control to the Control Center, but the button doesn't work or respond when pressed. The Caps Lock light works, but the keyboard backlight still won't come on, even in a dark room. What should I do to turn it on?