http://www.nikonchat.com/300mm-f-4-5-nikkor/

Nikon D100 Question?
I have a Nikon D100 and I have a Nikon AF Nikkor 70-300mm f/4-5.6D lens. For some reason when I try to use the aperature on the lens it says error on my camera. Is there a way like a certain setting that will aloow me to use the lens aperature instead of the digital aperature in the camera. Thanks.
On Nikon’s dSLR cameras the aperture setting is always controlled by the body, never by the aperture ring.
Lock the aperture ring in the minimum aperture – f/32.
Then switch your camera to aperture priority mode or manual mode and select the desired aperture with the scroll wheel at the front of the shutter button.
I suppose that’s exactly how you HAVE been doing it… but just in case. This method stops down the aperture blades in the same way as the conventional aperture ring would, so the effect is the same.
nikon 70-300mm f/4.5-5.6G ED IF AF-S VR Nikkor Zoom Lens for nikon digital slr Cameras