Young male breeding help

[Zombie]

There are lots of things. Mist them when you put them in a tub together, leave female's shed in the tub, put a different males shed in the tub, put another males sperm plugs on the back of the girl, put them together during a storm, pack the male up and take him for a ride in your car, there are all sorts of things you can try.

^^^^This pretty much covered it all
Also, don't try to pair him when he's in any stage of shed. Chances are he won't lock.