lua socket communication from c# receiving nil

Question

I'm trying to use lua script to extract some data from a program, and then send that data to a c# script which then processed it and returns some simple messages for the lua script to then pass along to the program.

The lua script is as follows

-- Socket decls
local socket = require("socket")
local host, port = "127.0.0.1", 3000
local tcp = assert(socket.tcp())
tcp:connect(host,port)
tcp:settimeout(0)
tcp:send("Stream starting...")

function sendEventInfoToServer(string)

    tcp:send(string)

end

function processEventInfo()
    local received, status = tcp:receive()

    if received ~= nil then
        print(received, status);
    end

end

while true do

     -- unrelated logic

    processEventInfo();
end

and on the C# end

public class SimpleTCPListener
{
    private TcpListener tcpListener;
    private TcpClient _tcpClient;
    private Thread listenThread;

    private NetworkStream clientStream;

    List<string> eventsWaiting;
    public List<string> EventsWaiting { 
        get {
            List<string> tempList = new List<string>();
            for (int i = 0; i < eventsWaiting.Count; i++)
                tempList.Add(eventsWaiting[i]);
            EventsWaiting = new List<string>();
            return tempList;
    } 
        private set { eventsWaiting = value; }
    }

    public SimpleTCPListener()
    {
        EventsWaiting = new List<string>();
        this.tcpListener = new TcpListener(IPAddress.Any, 3000);
        this.listenThread = new Thread(new ThreadStart(ListenForClients));
        this.listenThread.Start();
    }

    private void ListenForClients()
    {
        this.tcpListener.Start();

        while(true)
        {
            // blocks until a client has connected to the server
            TcpClient client = this.tcpListener.AcceptTcpClient();

            // create a thread to handle communication
            // with connected client
            Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientCom));
            clientThread.Start(client);

            clientStream = client.GetStream();
        }
    }

    public void SendSavestateLoadRequest()
    {
        if(clientStream != null)
        {
            ASCIIEncoding encoder = new ASCIIEncoding();
            byte[] buffer = encoder.GetBytes("HelloLua!\n");
            Console.WriteLine("Sending data back to lua");
            if (clientStream.CanWrite)
                clientStream.Write(buffer, 0, buffer.Length);
            else
                Console.WriteLine("Connection close!");
            //clientStream.Flush();
        }
    }

    private void HandleClientCom(object client)
    {
        TcpClient tcpClient = (TcpClient)client;
        NetworkStream clientStream = tcpClient.GetStream();

        byte[] message = new byte[4096];
        int bytesRead;

        while(true)
        {
            bytesRead = 0;

            try
            {
                // blocks until a client sends a message
                bytesRead = clientStream.Read(message, 0, 4096);
            }
            catch
            {
                // a socket error has occured
                break;
            }

            if(bytesRead == 0)
            {
                // the client disconnected
                break;
            }

            // message has been recieved
            ASCIIEncoding encoder = new ASCIIEncoding();
            System.Diagnostics.Debug.WriteLine(encoder.GetString(message, 0, bytesRead));
            string s = encoder.GetString(message, 0, bytesRead);
            Console.WriteLine(s);

            if (!string.IsNullOrEmpty(s))
                eventsWaiting.Add(s);
        }

        tcpClient.Close();
    }
}

Now, the Lua talks to the C# thread no problem, and the C# doesn't report any errors when sending data back to the lua, but on the lua side it's constantly receiving nil, however if I remove the nil check it sometimes receives and prints the string, but with the nil check it never seems to find 'received' as not nil. I'm really new with lua script so hopefully it's something simple I'm not understanding about the syntax but I can't seem to find lot of documentation.

Any suggestions would be hugely appreciated.