Can't make game windowed.

I have been working on a settings menu and I have hit a wall with a fullscreen option. I am using a toggle UI element with a method that contains this code:

Screen.fullScreen = !Screen.fullScreen;

The Unity website says this should easily switch the window modes but when I press my toggle box nothing happens. I have changed the default window mode in the player settings multiple times but nothing changes. Any help is appreciated.