Leage Of Legends (Brands Stun)

Ever since the latest patch update (6.21) I have noticed that sometimes my stuns for Brand do not work. I just got done playing a game where I used Brand's Conflagration (E) on Graves and quickly threw Brand's Sear (Q) at him, which should of stunned him. Instead I watched the fireball go straight through Graves with no effect and shortly after died. Please fix this bug quickly.