Can someone help troubleshoot this?

So here is the script:

function move()
	for k,p in pairs(game.Players:GetChildren()) do
		gui=p.PlayerGui:FindFirstChild("Notifications")
		print("Found gui")
		gui:WaitForChild("Frame")
		gui.Frame.Visible=true
		print("Visible")
		for i=1,30 do
			gui.Frame.Position=gui.Frame.Position+UDim2.new(0,0,.05,0)
			wait(.01)
		end
		print("Moved")
	end
end

It works once, but then if I try again, output tells me

Frame is not a valid member of ScreenGui

Script 'Workspace.Script', line 36 - global move

script 'Workspace.Script', Line 84

Stack End

The Line 84 is this: (I used -- to tell the line number in the actual script)

for k,plr in pairs(game.Players:GetPlayers()) do--81
			plr.PlayerGui.Notifications.Frame.TextLabel.Text="SFT2 has been loaded. Please wait for further instruction"--82
			plr.PlayerGui.Notifications.Frame.Visible=true--83
			move()--84
			wait(3)--85
			plr.PlayerGui.Notifications:Destroy()--86
			end	--87		

GUI Function:

function GUI()
	for k,plr in pairs(game.Players:GetPlayers()) do
		model=game.ServerStorage:FindFirstChild("Notifications")
		guiclone=model:Clone()
		guiclone.Parent=plr.PlayerGui
	end
end