I've made this userscript in order to use jScroll it in reddit.com and any subreddit

// ==UserScript==
// @name        Reddit jScroll
// @namespace   
// @include     http://www.reddit.com/*
// @version     1
// @grant       none
// @require     https://raw.githubusercontent.com/pklauzinski/jscroll/master/jquery.jscroll.min.js
// ==/UserScript==

$('span.nextprev').jscroll({
  contentSelector: 'div.content'   
});

where span.nextprev is the selector for the Next button
and div.content is the selector for the links content of every next page.

If open eg. reddit.com without login, then it works ok (it appends every next page).
The problem is when I try my userscript having login:
it only appends page 2, not the next pages
(it just shows Loading... at the end of the appended page 2 )
for example in:

1. http://www.reddit.com (I've only subscribed to 2 subreddits)
2. eg. http://www.reddit.com/r/firefox/

Is my userscript wrong or it'is jScroll?