What Is Wrong With This Chat Script's Private Message Function??

I Was Making A Private Message Function For My Chat But I Dont Know How To Only Get The Players Name And Then Get The Message After That, I Already Started With The Function So Here Is The Script: (and one error Saying: Line 132 bad argument #1 to "find" (string expected, got Object))

-- ROBLOX Services
local ContextActionService = game:GetService("ContextActionService")

-- Static variables
local MAX_MESSAGES = 5
local MESSAGE_HEIGHT = 25
local SpecialPlayers = {[148430515]='Co-Founder',[34929389]='Founder/Lead Developer'}
local PlayerColors = {[148430515]=Color3.new(255,170,0),[34929389]=Color3.new(255,0,0)}

-- Local variables
local player = game:GetService('Players').LocalPlayer
local messages = {}
local chatMessageEvent = game:GetService('ReplicatedStorage').CustomChat.PublicChat

-- Variables for GUI elements
local chatScreen = script.Parent.MainChat
local chatFrame = chatScreen.ChatFrame
local chatInput = script.Parent.ChatBar
local messageFrame = chatFrame
-- Make a copy of the message that will be used later
local messageTemplate = messageFrame.Message:Clone()
messageFrame.Message:Destroy()


local function addMessage(sender, message)
	-- Check if the number of messages has hit the maximum
	if #messages >= MAX_MESSAGES then
		-- If so add extra to the chatFrame
		chatFrame.CanvasSize = UDim2.new(0,0,chatFrame.CanvasSize.Y.Offset + 25,0)
		table.remove(messages,#messages)
	end
	
	-- Shift all of the messages up one slot
	for i = 1, #messages do
		local y = (MAX_MESSAGES - i - 1) * MESSAGE_HEIGHT
		messages[i].Position = UDim2.new(0, 0, 0, y)
	end	
	
	-- Create new message GUI elements and add to the message table
	local newMessage = messageTemplate:Clone()
    if sender.UserId == 34929389 then
	newMessage.Text = "Founder"..sender.Name .. ": "
	newMessage.Msg.Text = message
	newMessage.Parent = messageFrame
	newMessage.TextColor3 = Color3.new(255,0,0)
	newMessage.Position = UDim2.new(0, 0, 0, (MAX_MESSAGES - 1) * MESSAGE_HEIGHT)
	table.insert(messages, 1, newMessage)
elseif sender.UserId == 148430515 then
	newMessage.Text = "Co-Founder"..sender.Name .. ": "
	newMessage.Msg.Text = message
	newMessage.Parent = messageFrame
	newMessage.TextColor3 = Color3.new(255,170,0)
	newMessage.Position = UDim2.new(0, 0, 0, (MAX_MESSAGES - 1) * MESSAGE_HEIGHT)
	table.insert(messages, 1, newMessage)
else
	newMessage.Text = sender.Name .. ": "
	newMessage.Msg.Text = message
	newMessage.Parent = messageFrame
	newMessage.Position = UDim2.new(0, 0, 0, (MAX_MESSAGES - 1) * MESSAGE_HEIGHT)
	table.insert(messages, 1, newMessage)
	end
end

local function serverBroadcast(message)
	-- Check if the number of messages has hit the maximum
	if #messages >= MAX_MESSAGES then
		-- If so add extra to the chatFrame
		chatFrame.CanvasSize = UDim2.new(0,0,chatFrame.CanvasSize.Y.Offset + 25,0)
		table.remove(messages,#messages)
	end
	
	-- Shift all of the messages up one slot
	for i = 1, #messages do
		local y = (MAX_MESSAGES - i - 1) * MESSAGE_HEIGHT
		messages[i].Position = UDim2.new(0, 0, 0, y)
	end	
	
	-- Create new message GUI elements and add to the message table
	local newMessage = messageTemplate:Clone()
	newMessage.Text = "[Server]"
	newMessage.Msg.Text = message
	newMessage.Parent = messageFrame
	newMessage.TextColor3 = Color3.new(255,0,0)
	newMessage.Position = UDim2.new(0, 0, 0, (MAX_MESSAGES - 1) * MESSAGE_HEIGHT)
	table.insert(messages, 1, newMessage)
	end

local function addPrivateMessage(message,ToPlayer,FromPlayer) -- this is the function that errors
	if ToPlayer == player.Name then
	-- Check if the number of messages has hit the maximum
	if #messages >= MAX_MESSAGES then
		-- If so add extra to the chatFrame
		chatFrame.CanvasSize = UDim2.new(0,0,chatFrame.CanvasSize.Y.Offset + 25,0)
		table.remove(messages,#messages)
	end
	
	-- Shift all of the messages up one slot
	for i = 1, #messages do
		local y = (MAX_MESSAGES - i - 1) * MESSAGE_HEIGHT
		messages[i].Position = UDim2.new(0, 0, 0, y)
	end	
	
	-- Create new message GUI elements and add to the message table
	local newMessage = messageTemplate:Clone()
	newMessage.Text = "[From >"..FromPlayer.."> You]"
	newMessage.Msg.Text = message
	newMessage.Parent = messageFrame
	newMessage.TextColor3 = Color3.new(255,0,0)
	newMessage.Position = UDim2.new(0, 0, 0, (MAX_MESSAGES - 1) * MESSAGE_HEIGHT)
	table.insert(messages, 1, newMessage)
	end
	end

-- Function when the input TextBox looses focus
local function onFocusLost(enterPressed, inputObject)
	-- Check if TextBox lost focus because the user pressed "Enter"
	if enterPressed then
			-- check if the player sent a server broadcast
			if player.UserId == 34929389 or player.UserId == 148430515 then
				local cmd = string.sub(chatInput.Text,1,11)
				local ChatCmd = string.lower(cmd)
				if ChatCmd == "/broadcast " then
					local msg = string.sub(chatInput.Text,11)
					serverBroadcast(msg)
				end
			end
			local Msgr = string.sub(chatInput.Text,1,5)
			local MsgCmd = string.lower(Msgr)
			if MsgCmd == "/msg " then
				local players = game:GetService('Players'):GetPlayers()
				for index, value in ipairs(players) do
				local Player = string.sub(chatInput,string.find(chatInput, value))
				local Msg = string.sub(chatInput, Player)
				local From = player.Name
				game:GetService('ReplicatedStorage').CustomChat.PrivateChat:FireClient(Msg, Player, From)
				end
			end
			local cmd = string.sub(chatInput.Text,1,11)
			local ChatCmd = string.lower(cmd)
			if ChatCmd ~= "/broadcast " then
			-- Add the message to the GUI (no need to filter messages from the local player)
			addMessage(player, chatInput.Text)
			-- Send message to the server to get filtered and sent to other players
			chatMessageEvent:FireServer(chatInput.Text)
			-- Reset TextBox text
			chatInput.Text = ""
			chatInput.Visible = false
			chatInput.Text = ""
			chatInput.Visible = false
			chatInput.Text = ""
			chatInput.Visible = false
			chatInput.Text = ""
			chatInput.Visible = false
			chatInput.Text = ""
			chatInput.Visible = false
			end
		end
	end

-- Function when the player presses the slash key
local function onSlashPressed(actionName, inputState, inputObject)
	if inputState == Enum.UserInputState.End then
		-- If key up then capture focus in the TextBox so the user can start typing
		chatInput:CaptureFocus()
		chatInput.Visible = true
	end
end

-- Disable ROBLOX default chat
game.StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.Chat, false)

-- Bind functions
chatMessageEvent.OnClientEvent:connect(addMessage)
game:GetService('ReplicatedStorage').CustomChat.PrivateChat.OnClientEvent:connect(addPrivateMessage)
chatInput.FocusLost:connect(onFocusLost)
ContextActionService:BindAction("Chatting", onSlashPressed, false, Enum.KeyCode.Slash)