收集过滤器转换类型错误

我已经过滤了我的集合

这是我的代码

 public ICollectionView LogEntriesStoreView { get; set; }
  var collection = new ObservableCollection<Service>(this._model.GetService());
   this.LogEntriesStoreView = CollectionViewSource.GetDefaultView(collection);
            this.LogEntriesStoreView.Filter += new FilterEventHandler(ShowOnlyBargainsFilter);

private void ShowOnlyBargainsFilter(object sender, FilterEventArgs e)
        {
            AuctionItem product = e.Item as AuctionItem;
            if (product != null)
            {
                // Filter out products with price 25 or above
                if (product.CurrentPrice < 25)
                {
                    e.Accepted = true;
                }
                else
                {
                    e.Accepted = false;
                }
            }
        }

现在我得到这个错误隐式类型转换"System.Windows.Data. xml"。过滤EventHandler" in "系统。谓词"不能是

this._view = new TViewType();
            this._model = new ServiceModel();
            this.Service = new ObservableCollection<Service>(this._model.GetService());
            this.OkCommand = new RelayCommand(o => this.OKRun());
            this.LostFocusCommand = new RelayCommand(o => this.LostFocusOKRun());
            // в переменную получаем нашу коллекцию
            var collection = new ObservableCollection<Service>(this._model.GetService());
            // инициализируем поле типа ICollectionView нашей коллецией
            this.LogEntriesStoreView = CollectionViewSource.GetDefaultView(collection);
            this.LogEntriesStoreView.Filter = new Predicate<object>(Contains);
            this.LogEntriesStoreView.Filter += new FilterEventHandler(ShowOnlyBargainsFilter);

            this._view.SetDataContext(this);
            this._view.ShowIView();
        }
        private void OKRun()
        {
            MessageBox.Show("One Click");
        }
        private void LostFocusOKRun()
        {
            MessageBox.Show("LostFocus");
        }
        private void TextChanged()
        {
        }
        private void ShowOnlyBargainsFilter(object sender, FilterEventArgs e)
        {
        }
        public bool Contains(object de)
        {
            return true;
        }

完整代码，我在我的代码中添加了一个谓词。例如在msdn