Many people think wolves cannot be trained. It is true most accepted dog training techniques may fail with wolves. We have had success using behavior modification and positive reinforcement. We don't use painful or punitive methods. Even if an enormous amount of time is spent training a wolf - one cannot expect the consistency you would get with a dog with even less time spent.
Wolves have their own agenda - and are extremely intelligent.
They are often one-event learners. Your margin for error is small - with dogs your training mistakes are easier to fix. With most wolves, if you give one a bad experience - it may be impossible or at least very difficult to fix. Once while taking an adolescent wolf out of an enclosure the handler allowed the leash to clank on the metal gate post. This startled the wolf enough to cause her to refuse to allow herself to be leashed again.