My first guess is that this lens/adapter combination doesn't "talk" to the camera. The camera has no idea a lens is attached and therefore is giving you a message that the lens is not attached correctly, or however the camera interprets the issue.
That will most likely inform you of what to do and provide some guidance.
Chalybeateman wrote:
Recently on this site I got some advice on an old MC/MD 200 mm lens to fit my Sony A7 camera. As advised, I ordered an adaptor through Ebay. Seem to work OK in
attaching the lens to my camera. However, when I turned it on I got the following message. "Check the lens attachment. If the lens is not supported, you may permit
use of the lens in the custom menu." I have gone through my menu several times. I don't see a custom menu option.
Any advice or suggestions?