D5100 Lens error

Hello - I have D5100 that I just tried with my new 20mm Nikkor 2.8mm lens. In manual mode or any mode for that matter if I try and manually set the apperature I get a FEE error saying the lens is not locked. When I lock the lens it will not give the error but I cannot adjust the apperature manual mode or otherwise. I need to be able to adjust in manual mode.

Thanks for any help!

Regards,

Eric

Let me see if I understand your question - when the lens is locked and you are in "M" mode and the dial on the camera body has been moved from AF to M, you're saying that when you turn the sub-command dial to adjust the aperture you do not see it changing in the viewfinder? Is that right or am I confused?

I had a similar issue I seem to remember with a D70. The lens had to be either in the wide open or smallest aperture to work on the camera - can't remember which it was....