That's exactly how our son was at this time last year. Now, at 3.5, he's finally trained. He was interested in it when we would put him on it, but he wouldn't do it on his own. Then, during the fall, he wanted nothing to do with it. Finally, around the start of winter, he started getting better with it (as did we) and daycare helped tremendously. We were lucky, there were 8 boys in the same age group who were trained together at daycare. Now, he's goes on his own all day, and only wears a diaper at night. He has around 2 accidents a week, which isn't too bad, I don't think. I wouldn't stress it right now, keep introducing it to him, but let him take the lead. He'll get there with persistence and patience, but it has to be on his terms at this point. Boys train later than girls, on the whole, so for him to be 2.5 and not trained yet is no big deal.
Hope this helped you, good luck!