I took my camera ( Nikon D3100 ) out this morning. But it did not focus on the object. Discovered both 55mm and 200mm had the same problem. I can hear the motors, but no movement in the lens. Manual focus OK. Tried all different settings, with the same result. Is there something I have missed?. Have I accidentally changed a setting somewhere?. Is this a known problem?. etc. etc. IS IT BROKE. ???????