[GAMEPLAY] Aatrox ult not activating in ARAM

While playing an ARAM game as Aatrox, my ultimate ability would not activate for a while. I was spamming the button through most of a teamfight and it wasn't until the fight was almost over and I had left the fray that it finally activated (probably around 30x trying to activate it). In the next fight I was able to get it to activate, but it still took a little spamming of the button to get it to work.