In order for the aperture to be controlled by the camera's program or primary and secondary control knobs, the lens must be set to the smallest opening - or highest number value f stop. The aperture must be operated by the ring if it is not left in the smallest opening position.
The FEE code you are seeing refers to a communication error between the lens and the camera body. Sometimes, simply removing the lens from the body and reseating it to the body will solve the problem. While the lens is off the body, carefully inspect the gold colored contacts on the lens and mating contacts on the camera body. Remove any dirt or debris found, being careful not to allow it to fall into the camera - or land on the back glass of the lens.
I found another explanation and possible remedy that stated:
"A flashing "FEE" is an improperly set aperture ring in 99.9% of all
cases with this error message (i.e. user error). In very rare
circumstances it can be caused by a damaged aperture ring (small lug
broken from back edge) that can't "tell" the camera it is at the minimum
position. If the aperture rings on the lens is set to minimum
aperture (highest number) and locked there, but you still get a FEE
error, it's possible that sloppy tolerances are causing the lens
aperture ring to not move the little switch at the 8 o'clock position (on
the D70 lens mount) as far as necessary to get a proper indication of
minimum aperture. Try to see if the aperture ring (while locked) will move
slightly when mounted on the camera to clear the FEE error.
Another remote possibility is that the little switch at the 8 o'clock
position mentioned above is not functioning properly (sometimes they
get dirty). Try "exercising" it by moving it back and forth with your
finger, then try the lenses again. Usually FEE has nothing at all to do with CPU
contacts (with a reverse engineered third party lens anything is
possible I suppose), but it doesn't hurt to clean them to eliminate that
You can also try a different Nikon compatible lens. If the trouble is still present, the camera may need to be returned for repair. If the the problem goes away, then the issue is tied to the lens itself. This would mean the the lens needs repair.
I hope this helps and good luck! Please rate my reply - thanks!