Backgroundworker exits after first expression

I have a list view bound to an ObservableCollection. With that I want to mock a chat application with a WPF gui. To simulate some activity I wanted to use a Background worker who spams a little bit. But the worker always exits his loop after executing the first statment, so my question is: why does he do that and how to fix it?
here is the code so far:

  public partial class MainWindow : Window, INotifyPropertyChanged
{
    #region INotifyPropertyChanged Members
    public event PropertyChangedEventHandler PropertyChanged;
    #endregion

    private string pCurrentUsername;
    public string currentUsername
    {
        get { return pCurrentUsername; }
        set
        {
            pCurrentUsername = value;
            if (null != this.PropertyChanged)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("currentUsername"));
            }
        }
    }

    ObservableCollection<ChatPost> items = new ObservableCollection<ChatPost>();
    BackgroundWorker bgWorker = new BackgroundWorker();

    public MainWindow()
    {
        InitializeComponent();
        currentUsername = "Me";
        items.Add(new ChatPost("this", "that"));

        bgWorker.DoWork += new DoWorkEventHandler(mockBussiness);
        bgWorker.RunWorkerAsync();
        lvChat.ItemsSource = items;

    }

    private void mockBusiness(object o, DoWorkEventArgs args)
    {
        while (!bgWorker.CancellationPending)
        {  
            items.Add(new ChatPost("guy1", "Ey man!"));
            items.Add(new ChatPost("guy2", "What man?"));
        }

    }


    private void btSend_Click(object sender, RoutedEventArgs e)
    {
        items.Add(new ChatPost(currentUsername, tbMessage.Text));
    }
}

public class ChatPost
{
    public ChatPost()
    { }
    public ChatPost(string username, string message)
    { 
        this.username = username;
        this.message = message;
    }
    public string username { get; set; }
    public string message { get; set; }
}

So the only thing that gets executed (meaning printed) is one time "Ey man!"