Fatal error: Call to undefined function privatemsg_title_callback() in menu.inc on line 500

Alright,

So my drupal-based site works perfectly fine on localhost, and I recently got a free hosting account on x10hosting.com, just to try things out.
I've uploaded all of my files via Filezilla to the public_html area, but when I try to access my site, I get the following error:

Fatal error: Call to undefined function privatemsg_title_callback() in /home/*******/public_html/includes/menu.inc on line 500 (*'s are used for blanking out).

Line 500 of menu.inc is: $item['title'] = $callback($item['title']);
Which is included in the function: function _menu_item_localize(&$item, $map, $link_translate = FALSE)

Any suggestions/ideas that would help me?