media not playing on pageload in windows phone 7

See more:

C#

Mobile

XAML

Windows-Phone-7

Hi
I am working in a app which deals with playing media. I included a media element and added the files to be played. But i am unable to play them on page load. i am placing my code here

xaml

<MediaElement Height="Auto" HorizontalAlignment="Stretch" Margin="-12,-45,0,0" Name="mediaElement1"
 VerticalAlignment="Stretch" Width="Auto"  />

xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Tasks;
using Microsoft.Phone.Shell;


namespace Kids_rhymes
{
    public partial class Player : PhoneApplicationPage
    {
        MediaPlayerLauncher mediaPlayerLauncher;
        int position;

       
        public Player()
        {
            InitializeComponent();
            mediaElement1.AutoPlay= true;
            mediaPlayerLauncher = new MediaPlayerLauncher();              
        }      

        void  OnAppbarPauseClick(object sender, EventArgs args)
        {
            mediaElement1.Pause();
        }

        void OnAppbarPlayClick(object sender, EventArgs args)
        {
            string[] videos = new string[] { "abd.mp4", "hrf.mp4",};
            if (position > 0)
            {
                mediaElement1.Source = new Uri("/Videos/"+videos[position-1], UriKind.Relative);
                mediaElement1.Play();
            }
        }

        protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
        {
            base.OnNavigatedTo(e);
            position = int.Parse(NavigationContext.QueryString["position"]);
            //MessageBox.Show("position " + position);

            
        }

        private void OnAppbarStopClick(object sender, EventArgs e)
        {
            mediaElement1.Stop();
        }

       
    }
}

can any one tell me why auto play is not functioning here