Why doesn't this give me the kill?

Been chasing him for 10 minutes. As soon as i was going to kill him he flies into the ground. ‘‘but maybe it wasn’t on purpose’’ I checked the server replay and he pointed down into the ground on purpose.

Also for the people going to say that my aim is bad, it isn’t the gun mounted on the bottom paired with the low velocity is just hard to aim when someone is REALLY trying not to die.