Eclipse project explorer can't be switched to the view on working sets

Question

After "project explorer -> view menu -> top level elements -> working sets" being chosen, Eclipse doesn't switch the view from projects to working sets on project explorer. If package explorer is used instead, the change-over works fine. Why?

Answer 1

You probably havent selected any working sets. In the drop down menu of the project explorer view, you have a menu item called select working set.... Go there and choose what working sets you want to see.

Answer 2

In my situation, I don't want to create any working set. So I change the Top Level Elements option(the first item in the drop-down menu of the image on @Fredrik's answer). Just change it from Working Sets to Projects.