d300 with tokina 12-24 lens problem

I intend to use a tokina 12-24 w/angle lens with my d300 body for some coastal sunset scenes.I thought i would shoot some garden pics.just to try the lens out but using it in aperture mode the exposure shown is f0 and i cant change this to any other aperture figure i want.Other lenses are fine so i cleaned the contacts with deoxit wipes but still did not show the correct aperture ,i took a shot in p mode but the exposure was unknown.Has anybody had this experience with this lens,i purchased it a couple of years ago but have not used it, i may have this problem then but i cannot remember (a senior moment).