Command block not killing everyone within 50 block radius and on Y level 26

I'm making a minigame where all players within a 50 block radius and on Y level 26 will be killed, however, its just killing everyone in a 50 block radius without even considering being on Y level 26. Here is the command i'm using:

kill @a[distance=..50,y=26,gamemode=!creative]

Why is it not working? Am I doing this wrong? Essentially the point of this is once you are knocked out of the arena, you will be killed once you reach that Y level. Any help would be appreciated. I changed my gamemode to survival but it just kills everyone in a 50 block radius, not people in a 50 block radius AND on Y level 26.