Draven Ultimate

Hi Riot, I have been playing Draven for a while, and there is one thing about him that bugs me a lot. When I fire my ultimate right before I am about to die, it sometimes goes off, sometimes goes halfway, and sometimes goes the whole way. It is very frustrating to me that I cannot judge how far my ult will go if I am in danger of dying, as it appears to be random. Also, it is very frustrating when my mouse just goes slightly over the minimap and my ult fires the wrong direction, although I can prevent against that. Thank you!