Nikkor Lenses

hi, when ever i try to conect my sigma 80-200mm lens to my nikond80 body, it wont let me auto shoot, only manual i lost the guides so any help??

Saw a guy lately when i was out...he had a nikon 300 and was utilizing a fantastic searching lens which he stated was an 80-400mm VR. How great is this lens...he stated he utilizes it very a bit to steer clear of getting to alter lenses.