[GAMEPLAY] Braum's ulti right before death

I was playing Braum in TeamBuilder, then as I was using my ulti, I died before I landed but it still caused the ulti. After that, I looked at the skill bar and saw that it showed my ulti as still usable. So in the next teamfight, I tried to use it but it didn't allow me. I could press on it and see where it would go, but it didn't activate. Because of that, I had to guess when I could actually use it and that caused me some trouble.