Missing argument? Can someone help?

I was testing this script and on the Output is saying there's a missing argument, here's what it says:

23:07:05.802 - Argument 1 missing or nil 23:07:05.803 - Script 'Players.Player1.PlayerGui.ScreenGui.TextButton.LocalScript', Line 9 - global Down 23:07:05.803 - Script 'Players.Player1.PlayerGui.ScreenGui.TextButton.LocalScript', Line 26

Here's the script:

plr = game.Players.LocalPlayer
a = plr.Up.Value

function Down()
	for i,v in pairs(game.Workspace:GetChildren()) do
			if v.Name == "SpawnLocation" then
				vv = {v.Name}
				d = vv[math.random(1,#vv)]
				plr.Character.Humanoid:MoveTo(d.Position)
				a = false
			end
	end
end

function Up()
	for i,v in pairs(game.Workspace.Lobby:GetChildren()) do
		if v.Name == "SpawnLocationU" then
			vv = {v.Name}
			d = vv[math.random(1,#vv)]
				plr.Character.Humanoid:MoveTo(d.Position)
		end
	end
end
script.Parent.MouseButton1Down:connect(function()
	if a == true then
		Down()
	elseif a == false then
		Up()
	end
end)

You could try this:

replace the for loops with this

ch = game.Workspace:GetChildren()
for i = 1, #ch do
	if ch[i].Name == "SpawnLocation" then
		d = ch[(math.random(1,#ch))]
		plr.Character.Humanoid:MoveTo(d.Position)
		a = false
	end
end

If it gives you any errors then please post them.