Effect fades away when they buyer of my Game Pass died? [SOLVED]

This is a problem which my game pass effects wont last long when the buyer died. They will get the effect when they bought the pass, but it will fade away instantly when they died

game.Players.PlayerAdded:connect(function(plr)
    if isAuthenticated(plr) then
		local name = plr.Name
		if name then
			local check = game.Workspace:FindFirstChild(name)
			if check then
				checkHumanoid = check:FindFirstChild("Humanoid")
				if checkHumanoid then
					checkHumanoid.WalkSpeed = 16 * 2
				end
			end
		end
    end
end)

-- this do not work...
while checkHumanoid.WalkSpeed ~= 16 *2 do
	checkHumanoid.WalkSpeed = 16 *2
end

i already the Died event, still, it wont work, any answers?