Okay, I've just tried debugging again. My Window's name is app. Inside it, it has a thing called myInput. In that, there's a sf::Window. Inside that, there's something called _vfptr. It's value is NULL. Inside that there are 2 values, and both of them say "CXX0030: Error: expression cannot be evaluated." I'm not to good at debugging, so this is all I can find.