Gui not tweening from RemoteEvent?

So I'm trying to make a warhead script that sounds two alarms, then tweens a GUI that shows a countdown until the explosion. The sound part works, but not the GUI script.

SERVER SCRIPT

local event = game:GetService("ReplicatedStorage"):WaitForChild("Events"):WaitForChild("Warhead"):WaitForChild("TweenGui")
local sounds = game.Workspace.Sounds.Warhead
local Players = game:GetService("Players")

sounds.Announce:Play()
wait(4.2)
sounds.Siren:Play()
event:FireAllClients()
wait(90)
sounds.Explosion:Play()

LOCAL SCRIPT

local event = game:GetService("ReplicatedStorage"):WaitForChild("Events"):WaitForChild("Warhead"):WaitForChild("TweenGui")
local Player = game:GetService("Players").LocalPlayer
local Gui = Player.PlayerGui.WarheadTimer.Frame

event.OnClientEvent:Connect(function() 
    Gui:TweenPosition(UDim2.new(0.271, 0,0, 0),'Out','Quint',1,true)
end)