Placement preview for my furniture placement system not working. How to fix?

I am making a basic furniture placement system for my game, and I am having trouble with hiding the selection box (for previewing) after the player has placed the structure.

After the player has placed the structure, it still shows the SelectionBox, but I intended to make it disappear when the player places the structure.

I am having the particular trouble in Line #35 of the Script for the server.

Script for the server:

-- Script
local ReplicatedStorage = game:GetService("ReplicatedStorage")

local MousePositionEvent = Instance.new("RemoteEvent")
MousePositionEvent.Name = "MousePositionEvent"
MousePositionEvent.Parent = ReplicatedStorage

local MouseClickEvent = Instance.new("RemoteEvent")
MouseClickEvent.Name = "MouseClickEvent"
MouseClickEvent.Parent = ReplicatedStorage


-- Preview the placement
local function PreviewPlace(Owner, PositionBase, StructureBase)
    StructureBase.UserOwner.Value = Owner.Name -- Assign Owner

    local Position = CFrame.new(PositionBase)
    StructureBase:SetPrimaryPartCFrame(Position) -- Move the structure

    -- Make it look like it's being previewed
    local Selection = StructureBase.SelectionBox
    Selection.Color3 = Color3.new(0, 255, 0)
    Selection.Transparency = 0
end
MousePositionEvent.OnServerEvent:Connect(PreviewPlace) -- Mouse position event listener


-- Place the structure when the user clicks
local function Place(Owner, PositionBase, StructureBase, DestinationFolder)
    local NewStructure = StructureBase:Clone()

    NewStructure.Parent = DestinationFolder
    NewStructure.UserOwner.Value = Owner.Name -- Assign Owner

    -- Hide the selection box after player has placed structure [I AM HAVING TROUBLE WITH THIS!]
    local Selection = StructureBase.SelectionBox
    Selection.Transparency = 1

    print(Owner.Name .. " has ended placing a " .. NewStructure.Name .. "!")
end

MouseClickEvent.OnServerEvent:Connect(Place)

Script for the client:

-- LocalScript
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local MousePositionEvent = ReplicatedStorage:WaitForChild("MousePositionEvent")
local MouseClickEvent = ReplicatedStorage:WaitForChild("MouseClickEvent")

local Players = game:GetService("Players")
local Player = Players.LocalPlayer

local Mouse = Player:GetMouse()
local MouseCFrame
local MousePosition

local SelectedStructure = game.Workspace.OakWoodBeam -- The selected Strukchur
local SelectedStructureAmount = 3
local DestDir = game.Workspace -- Destination Folder for placed structures

local Placing = true -- Placing Status

Mouse.Button1Down:Connect(function() 
    SelectedStructureAmount = SelectedStructureAmount - 1

    if (SelectedStructureAmount == 0) then
        Placing = false
    end

    MouseClickEvent:FireServer(MousePosition, SelectedStructure, DestDir) -- Trigger function place() in server

    print (Placing)
    print (SelectedStructureAmount)
end)   

-- Updates the mouse CFrame, and updates server about it
function UpdatePosition()
    MouseCFrame = Mouse.Hit
    MousePosition = MouseCFrame.p

    if (SelectedStructureAmount >= 1 and Placing == true) then -- If structure amount is not yet 0
        MousePositionEvent:FireServer(MousePosition, SelectedStructure)
        return true
    else 

    if (Placing == false) then -- Place the Structure when the user clicks
        return false
        end
    end
end

-- Game loop [CLIENT]
while true do
    UpdatePosition()

    --print (Placing)
    wait()
end

How would I fix it?