Unexpected transport close after socket.emit

I've got an application which consists of three different parts.

1. There is a presenter website that shows some information which is delivered through a websocket with socket.io.

2. I've got a node.js server which takes the data from different users and sends it to the presenter to display it.

3. There is a small website used by the common users that generates the data shown by the presenter.

All communication between user <--> server and server <--> presenter is handled with socket.io 1.0.6.

Here is how it should work:

1. The presenter is registerd at the server

2. An user is registered at the server

3. The server sends a notification to the presenter, that a new user has registered

4. Another user is registered at the server

5. Again should the server send a notification to the presenter

So, I got the problem at point 5. Everything before works just fine. I checked the disconnect event and it gets fired after the first socket.emit(..) to the presenter.

Why is the connection closed and how can I keep it alive?

Following is some code which reproduces the problem for me:

var io = require('socket.io').listen(8000),
    us = require('underscore');

var users = [];

io.sockets.on('connection', function (socket) {
    socket.on('newUser', function(data) {
        users.push({
            name: data.name,
            gender: data.gender,
            role: data.role,
            socket: socket
        });

        if(data.role === "user") {
            sendToAll(getUsersByRole("presenter"), "registerUser", { 
                name: data.name, 
                gender: data.gender, 
                role: data.role
            });
        }
    });

    socket.on('disconnect', function(reason){
        console.log("Disconnected: " + reason);
    });
});

function getUsersByRole(role) {
    var roleUsers = [];
    for (var i = users.length - 1; i >= 0; i--) {
        if(users[i].role === role){
            roleUsers.push(users[i]);
        }
    }
    return roleUsers;
}

function sendToAll(users, name, msg) {
    us.each(users, function(user) {
        user.socket.emit(name, msg);
        user.socket.emit(name, { name:"test", gender: "f", role: "user" }); //this second emit is not sent. Why?
    });
}