Do you know why he doesn't like his photo taken? You need to work off of that first. Once that has been established, then you need to explain why you want one in the first place. If you cannot give him a good reason (in his mind) why he should have a picture taken with you, then it isn't going to happen.
First find out why he doesn't want to take a picture. Is it part of his culture not to take pictures? Does he have low self esteem and doesn't want to see himself? Is he just being stubborn? If it's a reasonable reason, just give up on the photo. Also tell him why you want it, and what you will use it for.