Usage of messaging center in xamarin form

I’m currently trying to use Messaging Center to update the count of a shopping cart amount the message is sent with the correct data but is never received, and I’m not sure if my implementation is right (Never used it before) I’m trying to send data from a method to a view model to update a view from an Observable List Count here is my implementation

    public class Panier : BaseViewModel
    {
        private ObservableCollection<SmartDevice> content;

        public Panier()
        {
            this.content = new ObservableCollection<SmartDevice>();
        }

        public ObservableCollection<SmartDevice> GetContent() { return content; }

        public void AddProduct(SmartDevice product)
        {
            this.content.Add(product);
            int data = this.CountPanier();
            MessagingCenter.Send(this, "update counter", data);
        }

        public int CountPanier()
        {
            return this.content.Count;
        }

    }

Here is my View Model receiving the data

    internal class AppShellViewModel : BaseViewModel
    {
        private int counter = 0;
        public int Counter
        {
            get { return counter; }
            set 
            { 
                MessagingCenter.Subscribe<Panier, int>(this, "update counter", (x, data) =>
                {
                    counter = x.CountPanier();
                    OnPropertyChanged();
                });
            }
        }
    }

>Solution :

first, you need to call Subscribe in your VM constructor, so that it will start listening for any incoming messages

MessagingCenter.Subscribe<Panier, int>(this, "update counter", (x) =>
   {
       Counter = x;
   });

then your send needs to use the same signature as the subscribe

MessagingCenter.Send<Panier,int>(this, "update counter", data);