Socketio error : "no client on the channel"

Question

I'm trying to call a socketio function from python, but I'm getting the following error message :

NoSocket: There are no clients on the channel: global

As I've just started using socketio, I'm not familiar with it, so I would like to know why am I getting this error.

Here is the python :

print "starting test"
while s <= total:
print total
    percent = (100 * s) / total
    print percent
    res["data"]["value"] = percent
    socket.broadcast_channel(json.dumps(res), channel="global")
    time.sleep(1)
    s = s + 1
print "test is over"

and here is the socketio part :

var socket = new io.Socket();
socket.connect();
socket.subscribe('global');

console.log('subscribed');

socket.on('message', function (message) {
var data = JSON.parse(message);
if (data.type == "init") {
    console.log("Receiving Init info");
}
else if (data.type == "record") {
    console.log("Receiving record info");
if (data.data.object == "progress-bar") {
        var elem = document.getElementById("myBar");
        elem.style.width = data.data.value + '%';
        document.getElementById("label").innerHTML = data.data.value * 1 + '%';
}
}
else {
    console.log("Receiving unknown data type : " + JSON.stringify(data));
}
});

Any idea why? Thanks in advance.