Why do these functions mess up my onMouseButton1Down() function?

I have a script that takes parts from a model named pack and creates buttons that each represent an item in a backpack. When working properly, if the button is clicked you can place the part that it represents on the ground. For some reason, the main function that makes the player able to place the item on the ground isn't working. I know the other functions (most likely the update() function) is messing it up because I tried deleting all but this one function and it worked by itself. My question is, how could other functions make a onMouseButton1Down() function not work? let me know if I need to clarify anything. thanks!

local BUTTON = script.Parent
local player = game.Players.LocalPlayer
local MFRAME = game.Players.LocalPlayer.PlayerGui.BackpackGui.MFrame
local IFRAME = game.Players.LocalPlayer.PlayerGui.BackpackGui.MFrame.IFrame
local OPEN = game.Players.LocalPlayer.PlayerGui.BackpackGui.Backpack:FindFirstChild("Open")
local mouse=player:GetMouse()
local RANGE = 15
local BP_SIZE = 20
------------------------------
wait(3)

local CURRENT = nil

MFRAME.Visible = false
-------------------------------

function backpackCheck()
	local pack = player.Pack
	local number_stuff = #pack:GetChildren()

	return number_stuff < BP_SIZE
end

function removeExample()
	local player = game.Players.LocalPlayer
	local char = player.Character

	local ex_check = char:findFirstChild("BACKPACK_EXAMPLE")

	if ex_check ~= nil then
		ex_check:remove()
	end
end

function rangeCheck(mouse)
	local player = game.Players.LocalPlayer
	local char = player.Character
	local torso = char.Torso

	return (torso.Position - mouse.hit.p).magnitude < RANGE
end

function do_remove_all(parent)
	local children = parent:GetChildren()

	for index, child in pairs(children) do
		child:remove()
	end
end



function onGuiClick(part)
	CURRENT = part
	update()
end


function update()
	local player = game.Players.LocalPlayer
	local char = player.Character
	local pack = player:findFirstChild("Pack")
	local pack2 = player:findFirstChild("Pack2")
	local pack_tab = pack:GetChildren()
	local Ipack_tab = IFRAME:GetChildren()

	if CURRENT == nil then print ("current is nil")
		local x = 0
		local y = 0
	
		for index, child in pairs(pack_tab) do
			local CHOICE_GUI = MFRAME.TextButton:clone()
CHOICE_GUI.Size = UDim2.new(0, 100, 0, 20)
CHOICE_GUI.Transparency = .4
CHOICE_GUI.BackgroundColor3 = Color3.new()
			local new_gui = CHOICE_GUI 
			new_gui.Position = UDim2.new(0, x, 0, y)
			new_gui.Text = child.Name
			new_gui.TextColor3 = Color3.new(255,255,255)
			new_gui.Name = child.Name
			new_gui.MouseButton1Down:connect(function() onGuiClick(child) end)
			new_gui.Parent = IFRAME
			new_gui.Visible = true
			local CHILD = pack:FindFirstChild(child.Name)
			CHILD.Parent = pack2
			
			y = y + 20
			
			if y > 240 then
				y = 0
				x = x + 100
				
			end
			
		end
			
		--cleanGui()
	end
	end

function do_remove_all(parent)
	local children = parent:GetChildren()

	for index, child in pairs(children) do
		child:remove()
	end
end

function rangeCheck(mouse)
	local char = player.Character
	local torso = char.Torso

	return (torso.Position - mouse.hit.p).magnitude < RANGE
end


function removeExample()
	local player = game.Players.LocalPlayer
	local char = player.Character

	local ex_check = char:findFirstChild("BACKPACK_EXAMPLE")

	if ex_check ~= nil then
		ex_check:remove()
	end
end


function onMouseMove(mouse)
	local player = game.Players.LocalPlayer
	local char = player.Character
	local torso = char.Torso
	local pack2 = player:findFirstChild("Pack2")
local pack_tab = pack2:GetChildren()
local partname = BUTTON.Text
local part = pack2:FindFirstChild(partname)

local CURRENT = part
	removeExample()
	

	if CURRENT ~= nil then
		if rangeCheck(mouse) then
			
			local example = CURRENT:clone()
			example.Name = "BACKPACK_EXAMPLE"
			example.Locked = true
			example.Transparency = 0.5
			example.Parent = char
			example.Position = mouse.hit.p
			do_remove_all(example)
			
		end
	end
end

function onButton1Down(mouse)
	local pack2 = player:findFirstChild("Pack2")
local pack_tab = pack2:GetChildren()
local partname = BUTTON.Text
local part = pack2:FindFirstChild(partname)
local player = game.Players.LocalPlayer
local char = player.Character
local example = char:FindFirstChild("example")
local CURRENT = part

	
	--if CURRENT ~= nil then
		if rangeCheck(mouse) then
			removeExample()
			print("clicked")

			CURRENT.Parent = game.Workspace
			CURRENT.Locked = false
			CURRENT.Anchored = false
			CURRENT.Position = mouse.hit.p
			CURRENT = nil
			--do_remove_all(example)
			--cleanGui()
			script.Parent.Visible = false
			script.Parent:Destroy() print("buttonremoved")
			update() print("primaryupdate")
			
			
	end
	end
	--end

function onKeyDown(key, mouse)
	if key == "r" then
		removeExample()
		local CURRENT = nil
	elseif key == "e" then
		local player = game.Players.LocalPlayer
		local pack = player:findFirstChild("Pack")
		local pack_tab = pack:GetChildren()

		for index, child in pairs(pack_tab) do
			local CURRENT = child
			onButton1Down(mouse)
			wait(0.1)
		end

		local CURRENT = nil
	end
end

while wait(3) do  
	update() 
	print("yesss")
end


function onMouseButton1Down()
	print("buttonclicked")
	mouse.Button1Down:connect(function() onButton1Down(mouse) end)
	mouse.Move:connect(function() onMouseMove(mouse) end)
	mouse.KeyDown:connect(function(key) onKeyDown(key, mouse) end)

end

BUTTON.MouseButton1Down:connect(onMouseButton1Down)