- Too dark. Low light to your eyes is already pitch black darkness to the camera.
- Focus is not established. You may be too near your subject. Move back. If you are beyond the minimum focusing distance then maybe the lens or camera is not in focus. Make sure AF is set on.
- Battery is low. It may be enough to power on but not enough to turn the lens.
- Wrong settings. Some smart cameras prevent you from getting humiliated. It would be best to return to full Auto mode.
- Memory full. To be sure you have enough space on the memory card, format it. Copy all pictures to your computer first as format erases all files then lays tracks for new ones. There is a format option in the camera's menu system.
- Memory card error. If the card is not full but damaged, then that's the cause. You will have to replace the memory card. Make sure to format the new card before using.
- Memory card door is open. Turn off camera then close the door.
- Buffer is full. This happens after you press the shutter release button for an extended period of time making the camera work like mad taking a series of shots then suddenly stops. The camera's buffer memory is full and has to save to the slow memory card. There is no choice but to wait for this to finish. This is normal.
- Lens (for dSLR's) is not mounted properly or electrical contacts in the mounts are dirty. Try cleaning then make sure you hear the click when you mount.
- Error message. It means something. Do not ignore it. Check the manual to see how to resolve it.
- Camera is damaged. If nothing seems wrong but nothing works then bring it to the authorized service center of your camera's brand. If you don't know where it is, check the papers that came with your camera or ask the store where you bought it from.
- Power is off. Classic!
Now you know!