Your HandleEvent() function is at fault. If you look at the documentation for this function in csBaseEventHandler, it will tell you that you must call the superclass implementation if you didn't handle the event yourself. It should be written like this:
bool GameManager::HandleEvent(iEvent& ev)
Better yet, you should just get rid of this function entirely from your code. Again, the documentation will tell you that you almost never have to implement this function in csBaseEventHandler-based classes.