Why my custom event in C# is not raised?

Question

It's not the first time I've created a Custom Event in C#. It boggles my mind why it doesn't work in this simple case.

I have a Publisher with Subscribers. In my main program, I instantiated 1 publisher and 2 subscribers. When addNews is called, Subscribers should receive the event NewPublication:

static void Main()
{
    Publisher publisher = new Publisher();
    Subscriber subscriber1 = new Subscriber("John");
    Subscriber subscriber2 = new Subscriber("Jane");

    publisher.AddNews("custom event NewPublication");   
}

In subscriber.cs I have:

public delegate void NewPublication(Publisher fromPublisher, String Message);

public class Publisher {

    private List<String> newsList = new List<String>();
    public event NewPublication newPublication;

    public void AddNews(String news) {
        newsList.Add(news);

        if (newPublication != null)
        {
            newPublication(this, news);
        }
    }
}

In Subscriber I have:

private String m_Name;
private event NewPublication newPublication;


public Subscriber(String name) {
    m_Name = name;
    newPublication += new NewPublication(subscriber_newPublication);
}

public void subscriber_newPublication(Publisher fromPublisher, String Message) {
    MessageBox.Show(m_Name + " is notified for " + Message);
}

It compiles, but when running, the event is never raised. Why not? How can I fix my code so that it does get raised?

What's really different from MSDN sample code: http://msdn.microsoft.com/en-us/library/w369ty8x.aspx