Create notification if already there is no notification created

I'm trying to make a notification manager script using unity's mobile notification package. It will create a notification if already there is no notification created. But currently, it's not working. Can you guys help me out? (I target Android devices)

 public class NotificationManager : MonoBehaviour
 {
     private int identifier;
     /////////////////////////////// //create notification///////////////////////////////////////////////////
     void CreateNotifChannel()
     {
         var c = new AndroidNotificationChannel()
         {
             Id = "notifi1",
             Name = "Beat Corona",
             Importance = Importance.High,
             Description ="Reminds the player to play the game",
         };
        AndroidNotificationCenter.RegisterNotificationChannel(c);
     }
    public void SendNotification()
     {
         var notification = new AndroidNotification();
         notification.Title = "Hey Doctor";
         notification.Text = "Your patient needs your your help.";
         notification.FireTime = System.DateTime.Now.AddMinutes(0.1f);
         notification.LargeIcon = "icon_1";
         notification.SmallIcon = "icon_1";
         AndroidNotificationCenter.SendNotification(notification, "notifi1");
         identifier = AndroidNotificationCenter.SendNotification(notification, "notifi1");
     }
     private void Start()
     {
 
         if (AndroidNotificationCenter.CheckScheduledNotificationStatus(identifier) != NotificationStatus.Scheduled)
         {
             SendNotification();
             CreateNotifChannel();
         }
     }
 
 }