My location popup script doesn't work?

So I made a script that's supposed to tell the player in which they neighborhood they are after they exit the current one (basically like the city names that appear in gta games) but it doesn't work:

game.Players.LocalPlayer.CharacterAdded:Wait()
local player = game.Players.LocalPlayer
local char = game.Players.LocalPlayer.Character
local hum = char:WaitForChild("HumanoidRootPart")
local pos = hum.Position
local gui = player.PlayerGui.mainGUI

function isInRegion3(region, point)
    local relative = (point - region.CFrame.p) / region.Size
    return -0.5 <= relative.X and relative.X <= 0.5
       and -0.5 <= relative.Y and relative.Y <= 0.5
       and -0.5 <= relative.Z and relative.Z <= 0.5
end

local nbh = {}
nbh.city= 
{
	name = "city",
	coords = Region3.new(Vector3.new(-821,0,644), Vector3.new(101,1300,1546))
}

local loc = "a"
local temploc = "a"

while true do
	wait(3)
	for _, v in pairs(nbh) do
		if isInRegion3(v.coords, pos) then
			loc = v.name
		else
			loc = "notcity"
		end 
	end
	if loc ~= temploc then
	~~make popup appear~~
		temploc = loc
	end
end

Despite the player being in the area of "city", the popup appears as "notcity", so I think the problem is in the part that detects whether or not the player is in the region.

Help?