Hello,
This is the first time I am using this forum so I don't know if this is how you ask a question. I was using my D4s with the Nikon 70-200 2.8. I have the setting on Manual. My focus button is on the AF-ON, the shoot button is just that to shoot not to focus. We were in a middle of a shoot and the camera decided not to fire. was not using a flash. it happened ones or twice than it worked. Then about 5-10 minutes later, I tried a few times and it would not fire. I shot the camera down for a while and then it seemed to fire. I am just concerned on why it did it without an explanation for future shoots. Has anyone experienced that?