FCM push notification not received in MyApp - xamarin

Question

Iam implementing FCM push notification using PHP script and below code, I want to send notification to all device which subscribed to topic with name (news), but when call my script no message recieved and i donnt know what is wrong
public override void OnMessageReceived(RemoteMessage message)
{
base.OnMessageReceived(message);
SendNotificatios(message.GetNotification().Body, message.GetNotification().Title);
}
public void SendNotificatios(string body, string Header)
{
Notification.Builder builder = new Notification.Builder(this);
builder.SetSmallIcon(Resource.Drawable.Icon);
var intent = new Intent(this, typeof(MainActivity));
intent.AddFlags(ActivityFlags.ClearTop);
PendingIntent pendingIntent = PendingIntent.GetActivity(this, 0, intent, 0);
builder.SetContentIntent(pendingIntent);
builder.SetSmallIcon(Resource.Drawable.Icon);
builder.SetContentTitle(Header);
builder.SetContentText(body);
builder.SetDefaults(NotificationDefaults.Sound);
builder.SetAutoCancel(true);
NotificationManager notificationManager = (NotificationManager)GetSystemService(NotificationService);
notificationManager.Notify(1, builder.Build());
}
}
}
MainActivity
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.Main);
msgText = FindViewById<TextView>(Resource.Id.msgText);
if (Intent.Extras != null)
{
foreach (var key in Intent.Extras.KeySet())
{
var value = Intent.Extras.GetString(key);
Log.Debug(TAG, "Key: {0} Value: {1}", key, value);
}
}
IsPlayServicesAvailable();
var logTokenButton = FindViewById<Button>(Resource.Id.logTokenButton);
logTokenButton.Click += delegate
{
Log.Debug(TAG, "InstanceID token: " + FirebaseInstanceId.Instance.Token);
};
var subscribeButton = FindViewById<Button>(Resource.Id.subscribeButton);
subscribeButton.Click += delegate
{
FirebaseMessaging.Instance.SubscribeToTopic("test");
Log.Debug(TAG, "Subscribed to remote notifications");
};
}
Manifest file
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.amgad.android" android:versionCode="1" android:versionName="1.0">
<uses-sdk android:minSdkVersion="15" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<application android:label="FCM">
<receiver android:name="com.google.firebase.iid.FirebaseInstanceIdInternalReceiver" android:exported="false" />
<receiver android:name="com.google.firebase.iid.FirebaseInstanceIdReceiver" android:enabled="true" android:exported="true" android:permission="com.google.android.c2dm.permission.SEND">
<intent-filter>
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
<action android:name="com.google.android.c2dm.intent.REGISTRATION" />
<category android:name="${applicationId}" /> </intent-filter>
</receiver>
</application>