SortedList没有'；I don’我好像在整理

我围绕SortedList创建了一个包装类。我向这个类添加对象，希望它们能自动按字母顺序排序，但当我绑定到WPF中的ListBox时，我会看到它们按未排序的顺序排列。

public class SortedObservableCollection<T> : ICollection<T>, INotifyPropertyChanged, INotifyCollectionChanged where T : INotifyPropertyChanged//, IComparable<T>
{
    private readonly SortedList<string,T> _innerSortedList;
    public SortedObservableCollection()
    {
        _innerSortedList = new SortedList<string, T>();
    }
    public void Add(T item)
    {
        _innerSortedList.Add(item.ToString(), item);
        this.OnPropertyChanged("Count");
        this.OnPropertyChanged("Item[]");
        this.OnCollectionChanged(NotifyCollectionChangedAction.Add, item);
        item.PropertyChanged += ItemPropertyChanged;
    }
    void ItemPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        throw new NotImplementedException();
    }
    public void Clear()
    {
        _innerSortedList.Clear();
    }
    public bool Contains(T item)
    {
        return _innerSortedList.ContainsKey(item.ToString());
    }
    public void CopyTo(T[] array, int arrayIndex)
    {
        throw new NotImplementedException();
    }
    public int Count
    {
        get { return _innerSortedList.Count; }
    }
    public bool IsReadOnly
    {
        get { throw new NotImplementedException(); }
    }
    public bool Remove(T item)
    {
        bool success = _innerSortedList.Remove(item.ToString());
        if (success)
        {
            item.PropertyChanged -= ItemPropertyChanged;
            this.OnPropertyChanged("Count");
            this.OnPropertyChanged("Item[]");
            this.OnCollectionChanged(NotifyCollectionChangedAction.Remove, item);
        }
        return success;
    }
    public IEnumerator<T> GetEnumerator()
    {
        throw new NotImplementedException();
    }
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        return _innerSortedList.GetEnumerator();
    }
    protected virtual void OnPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    protected virtual void OnCollectionChanged(NotifyCollectionChangedAction action, object item)
    {
        if (this.CollectionChanged != null)
        {
            this.CollectionChanged(this, new NotifyCollectionChangedEventArgs(action, item));
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    public event NotifyCollectionChangedEventHandler CollectionChanged;
}

绑定我只需：

SortedObservableCollection<IRCUser> Users { get; private set; }
.. fill users...
lstUsers.ItemsSource = users;

样本输入：

5Muhammad0
2Muhammad1
5Muhammad2

输出也显示出类似的情况，以2、4等开头的输出在5之间千疮百孔。

注意：我的IRCUser类确实实现了IComparable，但由于我现在只想要一个字母排序，我对实现进行了注释，希望默认排序能够生效。

注2：我已经覆盖了toString（）方法，我忘了提到它：

public override string ToString()
{
    return (int)Type + Nick;
}

更新：

在内部，sortedList似乎保持着正确的顺序，但它并没有以正确的顺序传递给ListBox。。。