You need to have his trust and respect that will lead to a connexion between you two.
If he doesn't trust you for any reasons, he won't jump because your are supposed to be his leader and he needs to count on you.
Horses are also a mirror of our state of mind, if you are afraid of the jump, he will feel it and be scared too, he won't jump.
Of course you need to lead him perfectly in order to make it easy for him (you can also encourage him by talking to him in a calm way).
But he also needs boundaries, he needs to find confort when he gives you what you want (stop the demand, congratulate him, give him a reward or a stroke) and inconfort when he doesn't (keep asking for what you want and intensify until he gives it to you), with time, he will understand that it is better for him to respond correctly to what you ask him.
You need to always be focused on the present moment with your horse and nothing else (not a fault you made before or your will to win or even personal problems) or he will feel that you are disconnected from him and won't put effort on the work.
Finally, you can create this bond by just go and see him, play with him, don't always just ride him or make him work, establish a real relationship between you two and he will do what you want :)