nav-collapse无法正常工作[Twitter Bootstrap]

Okay I'm just trying to do a basic navbar like they have over at the main bootstrap site. The problem is it's not working for some reason. I have the code pretty much exactly like they do. When I resize the window, the navigation goes away, but the icon in the top right with the three bars doesn't show up. So essentially the navigation just gets hidden. Any thoughts on this?Okay I'm just trying to do a basic navbar like