I'm thinking this is something I am doing but I'm not sure what... Scenario: Indoors, night, lighting was 2 incandescent lamps, 1 halogen(not directed at subject), against a light background(wall painted bone white), distance, about 12 feet from subject, using D70, 50mm/1.8 lens, manual mode, 1/80 shutter speed, F11, SB600 ttl. When I hit the button, the lens will drive itself all the way out and in and then finally focus but then when I push to take the shot, nothing. Sometimes if I hold the button down, it will fire but not all the time. I had this happen with the 28-70mm also. Forgot to mention it happens mostly when I rotate the camera vertical. Any help/suggestions would be greatly appreciated.