SSH connection response not updating my GUI immediately

Hi Guys,

I'm pretty new to Threading and delegates, I've got this simple little app that I was working on just to learn to use the SharpSSH library in my larger application. I wanted to get an active update to a rich text box that i have on my form everytime I i get a response from sending a runCommand method my RTB only seems to update when the sshexec connection is closed any tips or steering me in the right direction would be greatly appreciated :).

What i find a little strange is that it will write to the console but not to the RTB...

below is my class:
namespace ThreadedApplicationTest
{
    public partial class Form1 : Form
    {
        SshExec myShellExecutor = new SshExec("xxx.xxx.xxx.xxx","xx","xxxxx");
        string result = "";

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            myShellExecutor.Connect();
            result = myShellExecutor.RunCommand("ls");
            Console.WriteLine(result);

            richTextBox1.Invoke((ThreadStart)delegate() { updateRTB(result); });

            result = myShellExecutor.RunCommand("hostname");


            myShellExecutor.Close();

        }

        private void updateRTB(String s)
        {
            richTextBox1.AppendText(s);
        }
    }
}

Thanks!
Carlo