Adding a custom view controller to a storyboard

Question

I'm trying to add a custom root view controller (let's call it MyViewController) to my storyboard but every time I do so, I get a black screen, no warning, no error, no nothing, just a back screen. The strange thing is, if I log self.window.rootViewController the object is of MyViewController type. Also, if I use a standard UIViewController instead of MyViewController everything's fine. Did anybody encountered this strange issue before?