If you are sure the feature is in the on position in the menu, (be careful here, Nikon often uses a reverse logic, you have to turn it off to turn it on) you could try a system result using the button under the rubber cover. You could also take the battery out for a while. Electronics get glitches, my D100 has done some strange things, then later, it's fine and it never happens again.
Thanks. The system reset is a small button, I think you have to use a pencil point to press it, under the rubber cover on the side. Same cover that exposes the USB port and ac power port. It's shown in the instruction book.
Thank you for the tips. I did check that option and it is on. So, it must be not functioning anymore. I hesitate to do a total "reset" since I have some custom settings downloaded - i.e. curves and such, and would have to reload that all on. Oh well - I do like the function for artistic compositions, so I'll decide if I want to reset or get serviced. Thank you all for your suggestion