C# android timer dont work

Question

I try to make timer in android app.

This is code.

Doesn't work

public class Activity1 : Activity

    {

        int count = 1;

        TextView txv1;

        System.Timers.Timer t1;

        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,

            // and attach an event to it

           // Button button = FindViewById<Button>(Resource.Id.MyButton);

            txv1 = FindViewById<TextView>(Resource.Id.textView7);

            DateTime dt = DateTime.Now;

            //txv1.Text = dt.ToShortTimeString();

            txv1.Text = dt.ToLongTimeString();

            t1 = new System.Timers.Timer(100);

            t1.Elapsed += new ElapsedEventHandler(OnTimeEvent);

            //t1.Interval = 100;

            t1.Enabled = true;

            t1.Start();

        }

        private void OnTimeEvent(object source, ElapsedEventArgs e)

        {

            txv1.Text = count.ToString();

            count++;

        }

I need help.

Thanks