Don't know if it's the problem,,but I had a rifle with one that you had to slightly depress the peep sight to allow the button to be moved (unlocked). Then the sight would rotate upwards into position under spring tension.
Perhaps it was made that way so recoil wouldn't unlock the thing and have it spring into action on it's own,,,or maybe the one I had just didn't work right in the first place. Worth a look and a try.