New rotors, old hub...

Something I ran into on some adapter hubs and this probably isn't your case but I had some like 12 mm or something studs? I had some 5 and 4 and 1/2 to 5 on 4 and 1/2 adapters. You would put the half inch nuts on and they would seem to tighten on but then all of a sudden spin. Who knows they may have come with metric stuff? Careful please.....