how to reconnect proximity on windows phone - windows-phone-8

Question

i have two page...mainpage and proximitypage
first i goto proximitypage from mainpage.. and than i can create connection with anoher phone WP8,
if i go back to mainpage and than goto proximitypage again, i cant connect again..
im using code like this :
public asyc void proximity()
{
this._proximitydevice = ProximityDevice.GetDefault();
if (this._proximitydevice == null)
{
MessageBox.Show("Ponsel anda tidak didukung NFC!!!");
return;
}
PeerFinder.TriggeredConnectionStateChanged += PeerFinder_TriggeredConnectionStateChanged;
PeerFinder.Start();
}
void PeerFinder_TriggeredConnectionStateChanged(object sender, TriggeredConnectionStateChangedEventArgs args)
{
if (args.State == TriggeredConnectState.PeerFound)
{
WriteMessageText("Peer found. Keep your devices together until the connection is established.\n");
}
else if (args.State == TriggeredConnectState.Completed)
{
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
PhoneApplicationService.Current.State["RemoteHostName"] = args.Socket.Information.RemoteHostName.RawName;
PhoneApplicationService.Current.State["RemoteServiceName"] = args.Socket.Information.RemoteServiceName;
LaunchGame(args.Socket);
});
}
else if (args.State == TriggeredConnectState.Failed || args.State == TriggeredConnectState.Canceled)
{
MessageBoxResult mb = MessageBox.Show("Tidak dapat terhubung dengan ponsel lain. \nIngin menghubungkan kembali ??", "Incuqu", MessageBoxButton.OKCancel);
if (mb != MessageBoxResult.OK)
{
//e.Cancel = true;
NavigationService.Navigate(new Uri("/MainPage.xaml", UriKind.Relative));
}
else
{
PlayMultiplayer();
//Application.Current.Terminate();
}
}
}
i hope somebody can help...thanks