Not sure why you're surprised that the lenses work. That's one of the pluses of the Nikon system. Older lenses have the same mount and will work fine on newer cameras. At least, most of the newer cameras. Some of the AF lenses won't work on some of the lower end digital bodies that don't have the screw drive mechanism. WRT the AF lens that isn't working, that is strange, particularly if it won't work even in manual focus mode. In AF mode, there is a setting in the menus for focus priority or shot priority. Don't remember what setting it is and don't have the camera with me to check, but you could try switching that to shot priority if it isn't already to see if that makes a difference.