Advice on dodgy door lock please?!

[RickApple]

Hi guys n gals, ive just spent 2 years restoring a 91 mini and its finished - except for the fact that on my drivers side the lock doesnt work. I've taken the handle and lock off and the barrel mechanism works fine, its a brand new set from huddersfield mini spares. The interior locking switch [left-right pusher thing] seems loose and there is no click like on the other side. Ive dismantled the whole thing but can't see what could be wrong with it. Any ideas?

Ta muchly, apple