Lens not attached message on new Nikon lens?

"Lens not attached" message on new Nikon lens?

Added (1). I bought a lens on ebay and when I put it on it says "lens not attached", even tho I put it on correctly, it clicks n everything. My kit lens works just fine.

Added (2). Camera is Nikon D5100, lens that doesn't work is 85mm 1.8

Added (3). Is the lens broken? Is there anything I can do about t?

Which Nikkor 85 mm, f/1.8 lens did you buy?

Only Nikkor AF-S lenses can auto-focus on entry level cameras like the D5100. Nikkor AF lenses have to be manually focused when attached to a D5100, using the electronic rangefinder in the viewfinder

If you purchased a manual focus AI Nikkor lens, it can't be used on your D5100 since it does not contain a CPU, necessary for your camera to communicate with the lens.

These things are important that you know before buying any used lenses for your fine camera. Your user manual has a list of the lenses that can be used by your camera and those which can't.

In the future refer to it before buying another used lens.

If instead, the lens you did buy is a Nikkor AF or AF-S lens and the camera does not recognise it, before you return it as a DOA lens to the seller, take your camera and lens into a proper camera shop and have them look at them. They will be able to quickly determine if you 1) bought the wrong lens type or 2) that there's a problem with the lens itself

What lens is it? It's probably not fully compatible.