How To Bind a CheckBox inside a ListBox using MVVM in Windows Phone 8

my Propert is in a class that is being inherited by my ViewModel, and the setter is being set, but it only works when I move it out of the listbox.

or should I include the property here?:

 public void LoadItems()
        { 
            using(var db =new SQLite.SQLiteConnection(App.DB_Path))
            {
                var query = db.Table<ShoppingModel>().OrderBy(c => c.Item);
               
                foreach (var item in query)
                {
                    var items = new ShowingModel()
                    {
                        DisplayingItem = item.Item,
                        DisplayingPrice = item.Cost,
                        DisplayingQuantity = item.Qauntity,
                        DisplayingPackaging = item.Packaging,
                    };
                    ShoppingItems.Add(items);
                }
            }
        }

plus this doesn't work on wp8:

RelativeSource Mode=FindAncestor, AncestorType=ListBox