Broken Hecarim Ult

While playing as Hecarim during my past matches his ultimate's fear hasn't been doing it's job. I'll use it, slamming into people, but it won't activate his fear, and sometimes not even the damage. Every now and then the fear goes off but, with it not activating as often as it should ( all the time) it's really hurting him in team fights and his overall performance in the game.