I have a 4 years girl and I am trying to make my wife pregnant but its never happening again I want to know why ?

Woman can only get pregnant like 5 days out of the month. Keep trying. She could also go to the doctor and get help as to the best time to try and to make sure that everything is in working order. Good luck.

First, does your wife want to have a child?

Sarah

You need to ask for her opinion for another child. Then, you need to follow, Mesural Cycle. Take iron rich food in you diet with Vit. C.
You also need to get you and your wife checked by Doctor, for impotencies.

How long have you actually been trying? It is not unusual for it to take quite a few months. Most couples will become pregnant within a year of trying, but some will take a bit longer and that can be normal as well.

Maybe she is on birth control and you have to have sex in order to get pregnant.