Kiev Arsat lens to Mamiya 645 adapter

Hi all,

Bought a Kiev adapter to use my 55mm Arsat shift lens on my 645e; adapter will sit in camera mount, but will not spin to lock.

Am I missing something? Adapter clearance is close to shutter release, but it doesn't seem to be the problem.

Is the 645e mount different than a J or 1000s mount?

Found a post on photo.net that solves problem, mount on 645e is slightly smaller.