He needs to see his doctor to find out what the reason is for him "shooting blanks". A blood test will be able to show the level of hormones in his body. He may be lacking in the male hormones, which can be rectified by the doctor prescribing a hormone gel.
If that is not the problem, he would have to be referred to a specialist.
Another reason for men shooting blanks is that the scrotum gets too hot. When sitting too long as a lorry driver for example.
My husband experienced the same thing. He had low T. Ever since using the gel, he's shooting with a loaded gun. Just takes a blood test to find out his levels. Good luck!
You definately need to see a fertility specialist.
He should see a urologist.