Lux's E was not working for no apparent reason.

In this ARAM game, i was playing as Lux , in the middle of the game, after my death i couldn't use my E anymore. We lost it because of it --' no poke no use. Anyways not important, the matter is that I was not able to use my** E for no reason**, i took a screenshot but it appeared all black! Nice, lucky day hun? Anyways, In mid game, in my respawn moment i was not able to use E, I tried to recconnect and nothing happened. Hope you fix this or find what was the problem. It wasn't ranked, but if it was i bet my teammate and I wouldn't be happy about it! Thanks and i hope you fix it soon!