Why this socket code doesnt work?

[PT Exorcist]

TcpClient client = new TcpClient();
client.Connect("127.0.0.1", 21);
client.GetStream().BeginRead(buffer, 0, buffer.Length, new AsyncCallback(ReadCallBack), null);

static void ReadCallBack(IAsyncResult callback) {
int res = stream.EndRead(callback);
if (res == 0) {
return;
}

string str = Encoding.Default.GetString(buffer);
Console.WriteLine(str);

I don't understand why it doesnt work. It should connect to my ftp(and it does as i can see it in my ftp server) and receive a "Bullet ftp serv" message but it doesn't!
The problem seems to be that the ReadCallBack method doesnt even get fired..but why?!