Detect Part Leaving Region3?

Today I attempted to create a simple placement script where the player can place stuff (not added yet) but ran into some troubles. I was going to use the Touched event but created some issues so instead I'm using Region3. The selected part is being validated can "CanMove" is being set to true if it's inside the Region3 but adding an else statement doesn't seem to do anything. I even tried printing something and nothing happened.

A concept or an explaination is all I need. Thanks.

Below is my full script which I am using.

repeat wait() until game.Players.LocalPlayer ~= nil
repeat wait() until game.Players.LocalPlayer.Character ~= nil
repeat wait() until game:IsLoaded()

local Player = game.Players.LocalPlayer
local Character = Player.Character
local PlayerGui = Player:WaitForChild("PlayerGui")

local Mouse = Player:GetMouse()

Selected = nil
CanMove = false

local Barrier = game.Workspace.Barrier
local BarrierRegion = Region3.new(Vector3.new(0,0,0), Barrier.Size)
Barrier.CFrame = BarrierRegion.CFrame

wait(2)

Selected = workspace.bRICK -- Oops, caps.
CanMove = true

function move()
    if CanMove == true and Character.Humanoid.Health > 0 and Character ~= nil and Player ~= nil and Selected ~= nil then
        Selected.Position = Vector3.new(math.floor(Mouse.Hit.p.X), 0, math.floor(Mouse.Hit.p.Z))
    end
end

function color()
    if CanMove == true and Selected ~= nil then
        Selected.Color = Color3.fromRGB(255, 89, 89)
    elseif CanMove ~= true then
        Selected.Color = Color3.fromRGB(25,25,25)
    end
end

while wait() do
    color()

    local parts = workspace:FindPartsInRegion3WithWhiteList(BarrierRegion, {Selected}, 1000)    

    for i,v in pairs(parts) do
        if v == Selected then
            CanMove = true
        else
            CanMove = false
            print("Testing")
            -- Testing nor disabled CanMove works.
        end
    end

    if Selected ~= nil and Mouse.Target ~= nil and Mouse ~= nil and CanMove == true then
        move()
    end
end