Codeigniter JSON数据

I have problem loading data with AJAX and JSON.

If I hit register button, it keeps loading forever...

AJAX code

$(document).ready(function(){
$('#regForm').submit(function(e) {

    register();
    e.preventDefault();

    });

});


function register()
{
    hideshow('loading',1);
    error(0);

    $.ajax({
        type: "POST",
        url: "http://yoursitename.com/register/submit_registration",
        data: $('#regForm').serialize(),
        dataType: "json",
        success: function(msg){

            if(parseInt(msg.status)==1)
            {
                window.location=msg.txt;
            }
            else if(parseInt(msg.status)==0)
            {
                error(1,msg.txt);
                //alert(msg);
            }

            hideshow('loading',0);
        }
    });

}


function hideshow(el,act)
{
    if(act) $('#'+el).css('visibility','visible');
    else $('#'+el).css('visibility','hidden');
}

function error(act,txt)
{
    hideshow('error',act);
    if(txt) $('#error').html(txt);
}

The controller, where we take data

public function submit_registration() {

    if($_SERVER['REQUEST_METHOD'] == 'POST') {
        $name = $this->input->post("name");

        if(!$name) {
            die(msg(0, "Please insert Your name!"));
        }

        echo msg(1, "index.html");
    } else {
        exit('No direct script access allowed');
    }
}

My helper function, to give the json

function msg($status,$txt)
{
    return '{"status":'.$status.',"txt":"'.$txt.'"}';
}

Is Codeiginter using some extra stuff for JSON or I'm really missing something important?