Why is this script working only for the server and not for the clients?

by this i mean when you test the game with F8 you enter testmode without players just the server.

The script is server-side

local ts = game:GetService("TweenService")
workspace.Terrain.f0Tornado.Value = true
local tornado = game.Lighting.f0Tornado:Clone()
tornado.Parent = game.Workspace
tornado.Position = workspace.Supercell.Position
local tornadoTi = TweenInfo.new(60)
local tornadoGoalDown = {}
tornadoGoalDown.Position = tornado.Position - Vector3.new(0,tornado.Size.Y,0)
local tornadoDown = ts:Create(tornado,tornadoTi,tornadoGoalDown)
tornadoDown:Play()