Close event not fired on Heroku #57

Hello im experimenting with sockjs and when testing on localhost the close event fires and gives all connected users the message that a user just leave. But when i put my app on a online server it doesn´t fire that event!!

You can check it here.
http://er-u-count.herokuapp.com/

var cons = {};

var sockjs_echo = sockjs.createServer(sockjs_opts);
sockjs_echo.on('connection', function(conn) {
console.log('connection' + conn);

//SAY WELCOME
conn.write("Welcome");
//NOTIFY OTHER USERS THAT WE HAVE ARRIVED
broadcastmsg(conn.sesion+" Joined");

cons[conn.id] = conn;

conn.on('data', function(message){
    broadcastmsg(conn.sesion+" SAY: "+message);
});

conn.on('close', function() {
    console.log('close ' + conn);
    delete cons[conn.sesion];
    broadcastmsg(conn.sesion+" is leaving");
});

});

//HELPERS
function broadcastmsg(msg){
for(c in cons){
cons[c].write(msg);
}
}

Is there any way to see if a connection is still on?