If it's his first time breeding (and he's hot by the way), it may take him a few times to figure out what he's supposed to do. Unfortunately, they don't always perform like we'd like them to.

How old is he?

Have you tried to remove the sperm plug from another male and put it on her back? Have you tried heavily misting them both down when you put them together?

How about him with two females at the same time? Or leave some of her shed in the tub the next time she sheds and introduce them. If she's defecated before you put them together, leave it, rather than cleaning it up.

These are all tips I've used to try to get a reluctant male to breed. Some quite successfully.

However, it's all going to boil down to the individual animal.

And no - I don't think it's because he's an import - I think it's because he's just a male.