How to use math.random?

I'm having a bit of trouble with this. It says I can't use math.random, but I'm not sure what else to use. 'Up' is a member of the Player (There's a script for it). Could someone help me out?

s = game.Workspace:GetChildren()

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

function Up()
	for i,v in pairs(game.Workspace.Lobby:GetChildren()) do
		if v.Name == "SpawnLocationU" then
			plr.Character:MoveTo(math.random(2,v.Position))
		end
	end
end

game.Players.PlayerAdded:connect(function(p)
	game.Workspace.CharacterAdded:connect(function(char)
		if p.Up.Value == false then
			Down()
		elseif p.Up.Value == true then
			Up()
		end
	end)
end)

You probably have to specify what X/Y/Z Position you are using.