WPF ListView未正确呈现

我创建了一个ListView控件来显示连接到我的应用程序的用户。在我将CellTemplates添加到GridViewColumns之前，它工作正常。现在，当我将项目添加到列表中时，它不会显示。但是，如果我关闭并重新打开该列表，则会显示该项目。因此，该项似乎被正确添加，但控件在添加该项后没有呈现。代码如下。提前感谢您的帮助。

public class ncWindow
{   
    public Grid _Grid;
    public ListView lstConnectedUsers;          
    private GridView connectedUsersGrid;
    public List<ConnectedUserItem> roomUsers = new List<ConnectedUserItem>();
    public ncWindow(Grid grid)
    {                       
        _Grid=grid;
        Setter setter = new Setter();
        setter.Property = GridViewColumnHeader.VisibilityProperty;
        setter.Value = Visibility.Collapsed;    
        Style style = new Style();
        style.TargetType = typeof(GridViewColumnHeader);                
        style.Setters.Add(setter);              
        Style lcuStyle = new Style(typeof(ListViewItem));
        Trigger lcuTrigger = new Trigger();
        lcuTrigger.Property = ListViewItem.IsSelectedProperty;
        lcuTrigger.Value = true;
        Setter lcuSetter = new Setter(ListViewItem.ForegroundProperty,Brushes.Blue);
        FrameworkElementFactory textBlockFactory = new FrameworkElementFactory(typeof(TextBlock));
        textBlockFactory.SetBinding(TextBlock.TextProperty,new Binding("UserName"));            
        textBlockFactory.SetBinding(TextBlock.ContextMenuProperty,new Binding("Menu"));         
        DataTemplate textBlockDataTemplate = new DataTemplate();
        textBlockDataTemplate.VisualTree = textBlockFactory;
        FrameworkElementFactory imageFactory = new FrameworkElementFactory(typeof(Image));
        imageFactory.SetBinding(Image.SourceProperty,new Binding("ImgPath"));           
        DataTemplate imgDataTemplate = new DataTemplate();
        imgDataTemplate.VisualTree = imageFactory;
        GridViewColumn statusColumn = new GridViewColumn();
        statusColumn.Width = 10;
        statusColumn.CellTemplate = imgDataTemplate;
        GridViewColumn userColumn = new GridViewColumn();
        userColumn.Width = 100;
        userColumn.CellTemplate = textBlockDataTemplate;
        GridViewColumn clmUserID = new GridViewColumn();
        clmUserID.DisplayMemberBinding = new Binding("UserID");
        clmUserID.Width = 0;
        connectedUsersGrid = new GridView();
        connectedUsersGrid.Columns.Add(statusColumn);   
        connectedUsersGrid.Columns.Add(userColumn);                         
        connectedUsersGrid.Columns.Add(clmUserID);  
        connectedUsersGrid.ColumnHeaderContainerStyle = style;                          
        lstConnectedUsers = nc.GetNewListView();//new ListView();
        lstConnectedUsers.HorizontalAlignment = HorizontalAlignment.Right;
        lstConnectedUsers.Margin = new Thickness(0,2,2,34);     
        lstConnectedUsers.Width = 130;      
        lstConnectedUsers.View = connectedUsersGrid;                
        lstConnectedUsers.SelectionMode = SelectionMode.Single;
        lstConnectedUsers.ItemContainerStyle = lcuStyle;
        lstConnectedUsers.ItemsSource = roomUsers;
        grid.Children.Add(lstConnectedUsers);                   
    }           
    public void AddConnectedUser(ClientAccess.SVC.Client user, ClientAccess.SVC.Room room)
    {
        try
        {       
            UserContextMenu contextMenu = null;             
            contextMenu = new UserContextMenu(nc,user);                         
            contextMenu.Opened += (sender,args) => contextMenu.OnOpen();                
            ConnectedUserItem i = new ConnectedUserItem(){ ImgPath = "", UserName = user.UserName, UserID = user.UserID, Menu = contextMenu};                                                                                   
            roomUsers.Insert(0,i);                                                              
        }
        catch(Exception ex)
        {
        }
    }
    public void RemoveConnectedUser(ClientAccess.SVC.Client user)
    {
        try
        {
            ConnectedUserItem i = roomUsers.Find(delegate(ConnectedUserItem ii){return ii.UserID==user.UserID;});
            roomUsers.Remove(i);
        }
        catch(Exception ex)
        {
        }
    }   
}
public class ConnectedUserItem : INotifyPropertyChanged
{
    private string imgPath;
    private string userName;
    private int userID;
    private UserContextMenu menu;
    public event PropertyChangedEventHandler PropertyChanged;
    public string ImgPath
    {
        get { return imgPath; }
        set { imgPath = value; OnPropertyChanged("ImgPath"); }
    }
    public string UserName
    {
        get { return userName; }
        set { userName = value; OnPropertyChanged("UserName"); }
    }
    public int UserID
    {
        get { return userID; }
        set { userID = value; OnPropertyChanged("UserID"); }
    }
    public UserContextMenu Menu
    {
        get {  return menu; }
        set { menu = value; }
    }
    protected void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)            
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));          
    }
}
public class UserContextMenu : ContextMenu
{
    private ClientAccess.SVC.Client client;
    private MenuItem miSilence, miAddBuddy, miPrivateMessage;
    public UserContextMenu(ClientAccess.SVC.Client _client)
    {
        client = _client;
        miSilence = new MenuItem();         
        miSilence.Header = "Silence";
        miSilence.Click += miSilence_Click;
        miAddBuddy = new MenuItem();            
        miAddBuddy.Header = "Friends";
        miAddBuddy.Click += miAddBuddy_Click;
        miPrivateMessage = new MenuItem();          
        miPrivateMessage.Header = "Send Message";           
        miPrivateMessage.Click += miPrivateMessage_Click;
        Items.Add(miPrivateMessage);
        Items.Add(miAddBuddy);
        Items.Add(miSilence);                       
    }
    public void OnOpen()
    {
    }
    private void miSilence_Click(object sender, RoutedEventArgs e)
    {                   
    }
    private void miAddBuddy_Click(object sender, RoutedEventArgs e)
    {           
    }
    private void miPrivateMessage_Click(object sender, RoutedEventArgs e)
    {                   
    }
}