I've seen many questions and answers about SD cards not being found and all the associated responses and suggestions to deal with that problem, but mine isn't a matter of it not being found. It's not being found all the time. It's a SanDisk Extreme 64GB and usually it works fine. Today I powered up and everything worked as it's supposed to and the camera turned green and everything reacted as it should but when I pressed the camera photo button, it was dimmed and the ST-16 said "NO SD CARD" . Well, there was an SD card. So I took it out and re-seated it, thinking that might be the problem, but it wasn't. Still no SD Card found. I then powered both units down and re-booted and when it came up, everything worked and the camera saw the card, and the video and still photo buttons worked. Three hours later, on another shoot, same thing happened. The card was formatted in the camera through the ST-16 but it still wasn't found. 2 re-boots later it came back online, so I have no idea why it's sporadic when looking for the card. Any ideas? Thanks.