Is this a "Fotasy FD-NEX" adapter? On top of the adapter is a double ended white arrow. One end is marked "LOCK". The other end is marked "OPEN". Make sure that the word "LOCK" is aligned with the red dot on front of the adapter at the top. On my adapter the ring is very stiff to move. Mount the lens to the adapter. It doesn't matter if it is an older "Breech Lock" style lens with the the ring that twists or the newer "Bayonet" style where the body of the lens twists while mounting or dismounting.
This applies only to the old FL or FD style lenses and not the Bayonet style of the newer auto focus EF and EF-S lenses, since they started about 35 years ago or so.
Now move the ring to the "OPEN" position. The lens should now respond to the aperture ring on the lens. The idea is that you move the ring on the adapter to the "LOCK" position for wide open brightness to aid with manual focusing. Then move to the "OPEN" position to stop down to your chosen aperture for taking the picture.
I use this adapter almost daily on my A-6000 shooting all focal lengths of old FD lenses from 15 to 600MM. I also use a Metabones Ultra Speed Booster when I don't want the crop factor.
The aperture set on the lens will never show in the viewfinder.