How do I finish a script's function?

I'm just starting scripting, but still beginning. I'm working on this script (Pasted Below) but some functions within it aren't working, I could really use help fixing it. If you can, edit the parts that are needing to be fixing, because I'm not sure whats going on with it. Thanks.

THE SCRIPT:

system = script.Parent
is_playing = system.Playing
stage = system.Stage

weapons = game.Workspace.Weapons

hum_team = game.Teams["Humans"]
zom_team = game.Teams["Zombies"]

msg = nil
hint = nil
playing = false
interrupted = false

minutes = 0
seconds = 0

function displayHint(text)
	if(hint==nil)then
		hint = Instance.new("Hint")
		hint.Text = text
		hint.Parent = game.Workspace
	else
		hint.Text = text
	end
end

function removeHint()
	if(hint~=nil)then hint:remove() hint = nil end
end

function displayMsg(text)
	if(msg==nil)then
		msg = Instance.new("Message")
		msg.Text = text
		msg.Parent = game.Workspace
	else
		msg.Text = text
	end
end

function removeMsg()
	if(msg~=nil)then msg:remove() msg = nil end
end

function giveWeapons()
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p].TeamColor==hum_team.TeamColor)then
				weapons.Pistol.Value:Clone().Parent = player[p].Backpack
			end
		end
	end
end

function killPlayers()
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p].Character~=nil)then
				local h = player[p].Character:FindFirstChild("Humanoid")
				if(h.Health>0)then
					player[p].Character.Humanoid.Health = 0
				else
					if(player[p]:FindFirstChild("Dead")~=nil)then
						player[p].Dead.Value = false
						player[p].Class.Value = "Zombie"
						player[p].TeamColor = hum_team.TeamColor
					end
				end
			end
		end
	end
end

function resetPlayers()
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p]:FindFirstChild("Dead")~=nil)then
				player[p].Dead.Value = false
				player[p].Class.Value = "Zombie"
				player[p].TeamColor = hum_team.TeamColor
			end
		end
	end
end

function countPlayers()
	local count = 0
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p].Character~=nil)then
				count = count +1
			end
		end
	end
	return count
end

function countPlayersInTeam(team)
	local team_count = 0
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p].TeamColor==team.TeamColor)then
				team_count = team_count +1
			end
		end
	end
	return team_count
end

function assignZombies(amount)
	local valid_players = {}
	local player = game.Players:GetChildren()
	if(#player>0)then
		for p = 1, #player do
			if(player[p].TeamColor==hum_team.TeamColor)and
			(player[p].Character~=nil)then
				table.insert(valid_players,player[p])
			end
		end
	end

	if(#valid_players>amount)then
		while(amount>0)do
			local rand = math.random(1,#valid_players)

			local chosen = valid_players[rand]
			chosen.TeamColor = zom_team.TeamColor
			chosen.Character.Humanoid.Health = 0

			table.remove(valid_players,rand)
			amount = amount -1
		end
	end
end

function countDown()
	seconds = seconds -1
	if(seconds<0)then
		minutes = minutes -1
		seconds = 59
		if(minutes<0)then playing = false return true end
	end

	return false
end

function playZombies()
	if(countPlayers()<=3)then
		assignZombies(1)
	elseif(countPlayers()<=6)then
		assignZombies(2)
	else
		assignZombies(3)
	end

	is_playing.Value = true
	displayMsg("Human team, survive the zombie team for 15 minutes to win the game, or else zombies win!")
	giveWeapons(1)
	delay(5,removeMsg)

	interrupted = false
	playing = true

	minutes = 14
	seconds = 60

	while(playing==true)and(countDown()==false)do
		local humans = countPlayersInTeam(hum_team)
		local zombies = countPlayersInTeam(zom_team)

		if(minutes==9)and(seconds==59)then
			stage.Value = 2
			displayMsg("Fast Zombie unlocked! Zombie team, chat '/fastzombie' to play as one next time you respawn!")
			delay(10,removeMsg)
		elseif(minutes==4)and(seconds==59)then
			stage.Value = 3
			displayMsg("Kamikaze Zombie unlocked! Zombie team, chat '/kamizombie' to play as one next time you respawn!")
			delay(10,removeMsg)
		end

		if(seconds<10)then
			displayHint("Humans left: "..humans.." | Time left: "..minutes..":0"..seconds.." | Zombies: "..zombies)
		else
			displayHint("Humans left: "..humans.." | Time left: "..minutes..":"..seconds.." | Zombies: "..zombies)
		end

		if(zombies==0)then -- Zombies left the game? Try to assign another to keep the game running!
			if(countPlayers()>=2)then
				if(countPlayers()<=3)then
					assignZombies(1)
				elseif(countPlayers()<=6)then
					assignZombies(2)
				else
					assignZombies(3)
				end
			else
				interrupted = true
				break
			end
		end

		if(humans==0)then break end
		wait(1)
	end
	stage.Value = 1

	removeHint()

	if(interrupted==true)then
		displayMsg("There are not enough players to continue the game...")
	else
		if(playing==false)then
			displayMsg("Humans have won the match by successfully surviving for 15 minutes!")
		else
			displayMsg("Zombies have won by successfully infecting all humans within 15 minutes!")
		end
	end

	is_playing.Value = false

	killPlayers()
	wait(5)
	resetPlayers()

	removeMsg()
end

while true do
	wait(3)
	resetPlayers()
	if(countPlayers()>=2)then
		removeMsg()
		playZombies()
	else
		displayMsg("Waiting for two or more players...")
	end
end

On line 43, you never closed the if statement with 'end', you only closed the function

function removeMsg()
	if(msg~=nil)then msg:remove() msg = nil end
	end
end