Ok, I know what is happening - there is a software bug in the controller. It all has to do with the DJI Lab menu setting - "Fly Immediately". If this is on, and you turn on the controller after you turn on the drone, the camera buttons will not work. If you turn on the controller before you turn on the drone they will work. If you have the setting off, it does not matter what order you turn on the controller and the drone. Maybe I should get a "bug bounty"...