Windows Phone App navigation issues

Question

I have an application in which within one page i hit a web service and take response and save it into database and shown data into the list. next i have a refresh button to refresh and load the list again from web service. while refreshing if i click the device back button, then i am not redirected to the desired page instead it closes the application.

protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
   {
     Dispatcher.BeginInvoke(() =>
      {
       NavigationService.Navigate(new Uri("/MyApp/MSample.xaml", UriKind.Relative));
      });     
   }

Answer 1

pressing the back button takes you to the previous page, if it exists, otherwise you leave the app. As far as I know, it's not recommended to change this behavior as it would be confusing for users