Why is math.random() giving me problems?

So I have this script that is supposed to choose a random element of an array.

However, it isn't working.

Output gave me this: 17:06:56.907 - Workspace.Elections.Script:16: bad argument #2 to 'random' (interval is empty)

Here's the script:

while wait(0.1) do
	if script.Parent.SetUp.Value == true then
		SetUp.Value = false
		local MapChoices = {
			["Map1"] = "Map",
			["Map2"] = "Map",
			["Map3"] = "Map",
			["Map4"] = "Map",
			["Map5"] = "Map",
		}
		local ModeChoices = {
			["Mode1"] = "Mode",
			["Mode2"] = "Mode",
			["Mode3"] = "Mode",
		}
		local x = math.random(1, (#MapChoices))
		local y = math.random(1, (#ModeChoices))
		Choice1 = MapChoices[x]
		Choice1.Mode = ModeChoices[y]
		x = math.random(1, (#MapChoices))
		y = math.random(1, (#ModeChoices))
		Choice2 = MapChoices[x]
		Choice2.Mode = ModeChoices[y]
		x = math.random(1, (#MapChoices))
		y = math.random(1, (#ModeChoices))
		Choice3 = MapChoices[x]
		Mode = ModeChoices[y]
		wait(0.1)
	end
end