Nil value, when the model is actually there?

The error occurs on line 49, I've tried many different ways to fix this issue, but its the same type of issue each time.

The model gets placed into workspace and then when I try and move it back it wont get placed in saying its a nil value?

21:55:38.333 - Players.ArtificialSystem.PlayerGui.Viewmodel:49: attempt to index local 'PrimaryGunParent' (a nil value)

--[                     Variables                       ]]--   
local player = game.Players.LocalPlayer
local PlayerFolder = game.ServerStorage["18920BHAKJ_PlayerInventorys_1K12J3I1"]:FindFirstChild("Folder"..game.Players.LocalPlayer.UserId)
local GunFolder = PlayerFolder:FindFirstChild("GunFolder"..player.UserId)
local PrimaryValue = GunFolder.Primary
local SecondaryValue = GunFolder.Secondary
local UI = game:GetService("UserInputService")
debounce = true
local SecondaryGunParent = GunFolder:FindFirstChild(SecondaryValue.Value)
local PrimaryGunParent = GunFolder:FindFirstChild(PrimaryValue.Value)

--[[------------------------------------------]]--


--[[                        Functions                       ]]--

function PrimaryGun()
    PrimaryGunParent.Parent = game.Workspace
    print(PrimaryGunParent.Name)

end

function SecondaryGun()
    SecondaryGunParent.Parent = game.Workspace
    print(SecondaryGunParent.Name)
end

--[[------------------------------------------]]--


--[[                        Basically, when you press one and two ok                        ]]--

UI.InputBegan:connect(function(input)
local SecondaryGunParent = GunFolder:FindFirstChild(SecondaryValue.Value)
local PrimaryGunParent = GunFolder:FindFirstChild(PrimaryValue.Value)
if input.KeyCode == Enum.KeyCode.One then


    if GunFolder.Secondary.Value == game.Workspace then
        --going to gunfolder 
        SecondaryGunParent.Parent = GunFolder
    elseif SecondaryGunParent.Parent == GunFolder then
        --going to workspace
        PrimaryGunParent.Parent = game.Workspace
    end

elseif input.KeyCode == Enum.KeyCode.Two then
    if PrimaryGunParent.Parent == game.Workspace then
--moved to gun folder

        PrimaryGunParent.Parent = GunFolder
    elseif PrimaryGunParent.Parent == GunFolder then
        SecondaryGunParent.Parent = game.Workspace
--Secondary gun is in workspace
    end
end
end)


--[[----------------------------------------------------------------------------------]]--