Why is TeleportService not working?

I'm trying to teleport everyone in a server to someone else's server in a different game. Easy enough. Except it's not, since it's returning some crap about the user being offline, when they're CLEARLY not.

local teleportService = game:GetService'TeleportService'
local teleportin = false

function check(ayy)
	local success,errorMsg,placeId,instanceId = teleportService:GetPlayerPlaceInstanceAsync(ayy)
end

function checkifgood(arg)
	local suc,msg = nil,nil
	local coru = coroutine.wrap(function()
	suc,msg = pcall(check(arg))
	end)
	if suc then
		return true
	else
		return false
	end
end

function followPlayer(player, targetUserId)
	local success2,errorMsg,placeId,instanceId = teleportService:GetPlayerPlaceInstanceAsync(targetUserId)
	if success2 then
       	teleportService:TeleportToPlaceInstance(placeId, instanceId, player)
	else
		followPlayer(player,targetUserId)
	end
end



game.Players.PlayerAdded:connect(function(plr)
	plr.Chatted:connect(function(msg)
		if string.sub(string.lower(msg),1,8) == "teleport" and plr:GetRankInGroup(3288652) == 254 and plr:GetRankInGroup(3288652) ~= 255 and teleportin == false then
			game:GetService('TeleportService'):Teleport(string.sub(msg,10,string.len(msg)), plr)
			local teleporting = plr.UserId
			local aaaa = plr.Name
			teleportin = true
			repeat wait() until game.Players:FindFirstChild(aaaa) == nil and checkifgood(teleporting) == true
			for i,v in pairs(game.Players:GetChildren()) do
				followPlayer(v,teleporting)
			end
		end
	end)
end)

This is the error message:

HTTP 0 (HTTP 400 (HTTP/1.1 400 UserOffline))