Socket.io events working only in the same process

Question

I'm trying to use socket.io & sticky-session to pass messages to my clients.

The problem is that client which connect to one of the processes won't get messages from other processes, only from the process he is connected to.

How can I make web sockets to work across all processes?

Server.js:

var cluster = require('cluster');
var app = require('./config/express')(db);

// Init the server to run according to server CPU's
if (cluster.isMaster) {
    for (var i = 0; i < 4; i++) {
        cluster.fork();
    }
} else {
    app.listen(config.port, function () {
        console.log('Process ' + process.pid + ' is listening to all incoming requests');
    });
}

Process.js:

var http = require('http');
var express = require('express');
var app = express();
var server = http.createServer(app);

var io = require('socket.io').listen(server);
var ns = io.of('/ns');

var sticky = require('sticky-session');

if (!sticky.listen(server, 8080)) {
    // Master code
    server.once('listening', function() {
        console.log('server started on 8080 port');
    });
}

client.js:

var io = require('socket.io-client');
var serverUrl = 'http://localhost:8080/ns';
var conn = io.connect(serverUrl);

conn.on('malware', function(infectedProcess){
    console.log('infectedProcess: ' + infectedProcess);
});