It says it's a nil value but it's not? [SOLVED]

So, i am making a voice chat script and testing out the ban feature. It is supposed to check if the speaker is an admin, so only admins can use the ban feature. It just returns: 77, attempt to index local 'speaker' (a nil value) I tried copying and pasting from wiki but the error still repeats! Anyways, enough of this talking. Here is the code:

-- get banned and admins
local speakbanned = {}
local admins = {ARTEK22}
-- get sounds

local model = Instance.new("Model")
model.Name = "Chat Voice sounds"
model.Parent = workspace

local trains = Instance.new("Sound") -- make a new sound
trains.Parent = model
trains.SoundId = "rbxassetid://165384079" -- set id
trains.Looped = false -- dont loop

local no = Instance.new("Sound")
no.Parent = model
no.SoundId = "rbxassetid://151908665"
no.Looped = false

local only = Instance.new("Sound")
only.Parent = model
only.SoundId = "rbxassetid://132149993"
only.Looped = false

local scarce = Instance.new("Sound")
scarce.Parent = model
scarce.SoundId = "rbxassetid://528207007"
scarce.Looped = false


for i,v in pairs(game.Players:GetChildren()) do -- when somebody joins
	
	local sgui = Instance.new("ScreenGui") -- gui making procces
	sgui.Parent = v.PlayerGui

	local frame = Instance.new("Frame")
	frame.Parent = sgui
	frame.BackgroundColor3 = BrickColor.Black().Color
	frame.Position = UDim2.new(0, 200, 0, 25)
	frame.Size = UDim2.new(0, 300, 0, 300)

	
	
	local title = Instance.new("TextLabel")
	title.BackgroundTransparency = 1
	title.TextStrokeTransparency = 0
	title.Parent = frame
	title.TextScaled = true
	title.TextColor3 = BrickColor.White().Color
	title.Text = "Chat Voice"
	title.Size = UDim2.new(0, 300, 0, 50)

	local info = Instance.new("TextLabel")
	info.BackgroundTransparency = 1
	info.TextStrokeTransparency = 0
	info.Parent = frame
	info.TextScaled = true
	info.Position = UDim2.new(0, 000, 0, 75)
	info.TextColor3 = BrickColor.White().Color
	info.Text = 'Type in "voicechat/commands" to see the commands!'
	info.Size = UDim2.new(0, 300, 0, 50)

	local textButton = Instance.new("TextButton")
	textButton.BackgroundColor3 = BrickColor.Red().Color
	textButton.TextColor3 = BrickColor.White().Color
	textButton.Parent = frame
	textButton.Position = UDim2.new(0, 100, 0, 200)
	textButton.Size = UDim2.new(0, 100, 0, 50)
	textButton.TextScaled = true
	textButton.Text = "Got it!"

	textButton.MouseButton1Down:Connect(function()
		frame:Destroy()
	end)
	
	v.Chatted:connect(function(msg, speaker) -- when somebody says something
		print(speaker.Name)
		if string.lower(msg) == "i like trains" then -- check if the message is "i like trains"
			trains:Play() -- play the sound
		elseif string.lower(msg) == "no" then
			no:Play()
		elseif string.lower(msg) == "i am the one and only" then
			only:Play()
		elseif string.lower(msg) == "hey whats up guys its scarce here" then
			scarce:Play()
		elseif string.lower(msg) == "voicechat/commands" then
			local m = Instance.new("Message")
			m.Parent = workspace
			m.Text = "Sorry, 'voicechat/commands' is under construction."
			wait(3)
			m:Destroy()
		elseif string.lower(string.sub(msg, 1, 14)) == "voicechat/ban/" and tableContains(admins, speaker.Name) then
				local number = #speakbanned + 1
				print(number)
		end
	end)
end

and here is what part i am having trouble with.

		elseif string.lower(string.sub(msg, 1, 14)) == "voicechat/ban/" and tableContains(admins, speaker.Name) then
				local number = #speakbanned + 1
				print(number)
		end