WHY DOESN't MY ROKINON FE8M-N 8MM FISHEYE LENS WORK ON MY NIKON D3100? - 1

I JUST GOT A ROKINON FE8M-N 8MM FISHEYE LENS AND I OPENED IT WITH JOY AND THEN ONCE I PUT IT ON MY NIKON D3100 IT SAID THERE WAS NO LENS ATTACHED DOES ANYONE NO WHY?
AND IS THERE A Way TO FIX IT?

The lens you bought is a manual, not electronic lens. Try putting your D3100 on manual, manual focus, everything manual. My D90 works with the old manual lenses but I have to make all determinations about exposure because the camera does not see the lens.

I'm sure that is your problem. You bought a simple off market lens with no means of communicating with a sophisticated digital device and that's all that is wrong. If the lens mount fits (Nikon f-mount), it'll work.

It's not a Canon, if the mount is Nikon it'll work but only in Manual mode.