Lee Sin Q bug #[gameplay]

Hi guys, This happens to me really often vs Tristana. When i Q her, she try to escape while jumping over the wall. Yeah u got i Q again to get her while she is exactly over the wall. Well normally i should follow all the way up thats how it is when i do it on free places like lanes, but in the vid u can see that i get stuck into the wall and loose the kill. Luckily a Brand show up but tough i would have a double kill there.