I think that all kids have different sleep habits/needs. I have 2 boys, both very different sleep needs. I have talked to my pediatrician about naps, and he said that my 16 month old needs at least 2 hours of nap time a day. Since my son only takes one nap (and always has been that way), then he must stay in his crib for 2 hours. I have tried many different approaches to this, and I have chosen to teach him to sleep by letting him cry a little (my pediatrician is for this method). I made sure that with naps I was consistent in time and place (always in his crib with a room with room darkening blinds at 1:15PM), same routine as nightime, and then I lay him down. If he gets up before 2 hours, I let him play in his crib for the remaining time. At first, he would cry for a little. After about 7 days of that, he caught on and now plays. He isn't sleeping, but it is quiet time which he needs. So, it is up to you to do what you feel comfortable with. If you aren't comfortable with him crying some, then just go in and rock him for a little bit (make it boring, no eye contact, lights, etc)....whatever you are comfortable doing.
If you try to no avail, then maybe try putting him down earlier at night. That may help. He may get up earlier in the morning, and then take a nice nap. Another thing to do is to make sure he is getting a lot of exercise play in the morning....always keep him moving. This should wear him out in time for a nap. Are you involved in any classes? Music class seems to wear my little guy out.
Good luck!