Why is the variables getting confused, is there a mistake in the script?

--[[Died version-
This works as well, even better actually, but I just tried to give you a solution based on your format. I just correct your mistakes
]]

local player = game.Players -- If the script doesn't work put game.Players["PLAYERNAME"]
local zombie = script.Parent.Zombie
local db = false

zombie.Humanoid:Died:connect(function()
if (db == false) then
	db = true
	player.RealMoney.Value = player.RealMoney.Value + 10
	db = false
	end
end)

--try this
--This will only run once

local player = game.Players -- This has to be defined furthermore
local zombie = script.Parent.Zombie

if zombie.Humanoid.Health <= ("0") then -- you had > instead of < 
player.RealMoney.Value = player.RealMoney.Value + 10
end