I have some problem some people help to run this code for me

Hi everybody I have some problem. Before now I can run this code but this time I can't when I run the application is shut down. Someone can test this code for me if you can I will check my phone. Thank you for help my.

using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using System.Net;
using System.Net.Sockets;
using System.Net.NetworkInformation;

namespace top
{
    [Activity (Label = "top", MainLauncher = true)]
    public class MainActivity : Activity
    {
        int count = 1;
        public TextView _tv;

        protected override void OnCreate (Bundle bundle)
        {
            base.OnCreate (bundle);

            // Set our view from the "main" layout resource
            SetContentView (Resource.Layout.Main);

            // Get our button from the layout resource,

            _tv = FindViewById<TextView>(Resource.Id.txtIP);
            _tv.Text = "YOUR IP :" + GetLocalIP ();
            // and attach an event to it
            Button button = FindViewById<Button> (Resource.Id.myButton);

            button.Click += delegate {
                button.Text = string.Format ("{0} clicks!", count++);
            };


        }

        private string GetLocalIP()
        {
            IPHostEntry host;
            host = Dns.GetHostEntry (Dns.GetHostName ());
            foreach (IPAddress ip in host.AddressList)
            {
                if (ip.AddressFamily == AddressFamily.InterNetwork)
                    return ip.ToString ();
            }
            return "127.0.0.1";
        }

    }
}