Adapter woes for Oshiro 8mm f3.5 Nikon mount to Sony NEX

[wlemann]

Here is my problem:

I am trying to attach an Oshiro 8mm f3.5 fisheye with to a Vello Nikon F to Nex adapter.  The squib for the lens says it is both full-frame and APC. The lens seats on the Nikon side of the adapter but, at least for me, will not twist and lock.  Note the adapter has retractable pin on the Nikon side.  This seems to allow release of the lens from the adapter.

What is wrong here?  Am I putting lens on wrong?  I think I have tried every combination of slots and tabs to no avail.  Do I need a different adapter?

The lens is AF and totally dumb to the Sony A7R2.

[wlemann]

Correction:  Fisheye lens is solely MF.

[mcbroomf]

I don't want to insult, but do you know that the Nikon mounts the opposite way to Sony and Canon?  I just wanted to confirm you're twisting it the correct way 
If that's not the problem then you may have a faulty adapter.  Perhaps posting a shot of the lens mount and adapter might help.