Nikon MBD 11 issues
There are two places where things could go wrong. Menus -- Custom>D13& D14,F5,F10.
Electrical contacts — as the previous poster cited. I live close to the beach, so every few months I take a "SMALL AMOUNT" of ISO alcohol on a bit of cotton and swab the contacts on the back of every lens, and on the body inside the lens mount.
I do the same using a Q-tip applicator with my MB-D11, and the matching contacts on the underside of the camera body.
For a quick check on these, take off the battery grip and then mount it again. Repeat a few times. The friction might dislodge corrosion.
My grip is on 6 weeks old. Camera is coming up on one year. I tried to save money by buying a Chinese imitation. The darn thing would work, and would discharge batteries, even with the power switch off.
And you do know, don't you, that the small rotary switch surrounding the shutter switch (on the grip) only affects the shutter button. It does not disable power on the grip.