System message script wont work

[foodislife345678]

I have a system message that should show up every time an admin joins:

Scripts

Main Script in ServerScriptService

--// Services \\--
local Players = game:GetService("Players")
local Lighting = game:GetService("Lighting")
local ServerScriptService = game:GetService("ServerScriptService")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local ChatService = require(ServerScriptService:WaitForChild("ChatServiceRunner"):WaitForChild('ChatService'))

--// Settings \\--
local Prefix = '/'
local Admins = {}
Admins[216571167] = {Rank = 'Owner', Name = 'foodislife345678'}
Admins[118600368] = {Rank = "Friend", Name = 'untred'}

--// Variables \\--
local AdminJoinedEvent = ReplicatedStorage.AdminJoined

--// Functions \\--
local function checkForTarget(target)
	if not target then
		warn('Target not found!')
	else
		print('Target found!')
	end
end

--// Commands \\--
local function onPlayerAdded(Player)
	if Admins[Player.UserId] then
		AdminJoinedEvent:FireAllClients(Player)
		Player.Chatted:Connect(function(msg)
			local loweredString = string.lower(msg)
			local args = string.split(loweredString," ")
			local args2 = string.split(loweredString, ",")
			
			--/time <add/set> <time>
			if args[1] == Prefix..'time' then
				local typ = args[2]
				local time_ = args[3]
				if typ == 'set' then
					Lighting.ClockTime = time_
					if time_ == 'day' then
						Lighting.ClockTime = 14
					end
					if time_ == 'night' then
						Lighting.ClockTime = 0
					end
				end
				if typ == 'add' then
					Lighting.ClockTime = Lighting.ClockTime + time_
				end
				if typ == 'subtract' then
					Lighting.ClockTime = Lighting.ClockTime - time_
				end
			end
			
			--/kill <target>
			if args[1] == Prefix..'kill' then
				local target = args[3] and Players:FindFirstChild(args[2])
				local valid = target and checkForTarget(target)
				if valid then
					target.Character:BreakJoints()
				end
				Player.Character:BreakJoints()
			end
			
			--/gamemode <gamemode> <target>
			if args[1] == Prefix..'gamemode' then
				local gamemode = args[2]
				local target = args[3] and Players:FindFirstChild(args[3])
				local valid = target and checkForTarget(target)
				if valid then
					if gamemode == 'creative' or '1' or 'c' then
						target.Character.Humanoid.MaxHealth = math.huge
						target.Character.Humanoid.Health = 9e9
					end
					if gamemode == 'survival' or '0' or 's' then
						target.Character.Humanoid.MaxHealth = 100
						target.Character.Humanoid.Health = target.Character.Humanoid.MaxHealth
					end
				end
				if gamemode == 'creative' or '1' or 'c' then
					Player.Character.Humanoid.MaxHealth = math.huge
					Player.Character.Humanoid.Health = 9e9
				end
				if gamemode == 'survival' or '0' or 's' then
					Player.Character.Humanoid.MaxHealth = 100
				end
			end
			
			--/tp|teleport <X,Y,Z/target>
			if args[1] == Prefix..'teleport' or args[1] == Prefix..'tp' then
				local X = args[2]
				local Y = args2[3]
				local Z = args2[4]
				local target = Players:FindFirstChild(args[2])
				local valid = target and checkForTarget(target)
				if valid then
					Player.Character.HumanoidRootPart.CFrame = target.Character.HumanoidRootPart.CFrame
				end
				Player.Character.HumanoidRootPart.CFrame = CFrame.new(X,Y,Z)
			end
		end)
	end
end


for _, player in pairs(Players:GetPlayers()) do
	onPlayerAdded(player)
end

Players.PlayerAdded:Connect(onPlayerAdded)

Localscript in StarterGui

local StarterGui = game:GetService("StarterGui")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local AdminJoinedEvent = ReplicatedStorage:WaitForChild('AdminJoined')
local Admins = {}
Admins[216571167] = {Rank = 'Owner', Name = 'foodislife345678'}
Admins[118600368] = {Rank = "Friend", Name = 'untred'}

AdminJoinedEvent.OnClientEvent:Connect(function(plr)
	local rank = Admins[plr.UserId]["Rank"]
	local name = Admins[plr.UserId]["Name"]
	if rank == 'Owner' then
		StarterGui:SetCore('ChatMakeSystemMessage', {
			Text = "{System}: The owner has joined!",
			Color = Color3.new(255,255,255),
			Font = Enum.Font.SourceSansBold,
			TextSize = 20
		})
	else
		StarterGui:SetCore('ChatMakeSystemMessage', {
			Text = "{System}: "..rank.." "..name.." has joined!",
			Color = Color3.new(255,255,255),
			Font = Enum.Font.SourceSansBold,
			TextSize = 20
		})
	end
end)

The thing is, it doesn’t work in the actual game, and only works in studio.
And when I check the console, there are no errors or anything.
If you know how I can fix this then please tell me!

– food