Ajax not working

I'm trying to use "Ubercart Ajax Cart" for Authcache ( http://www.ubercart.org/node/13521 ) without luck since all ajax calls fail.
I'm posting it here because the module seems not be maintained anymore and because other people will search for Authcache ajax problems here. Hope this is ok :)

Firebug says:

GET http://localhost/tickets/?uc_ajax_cart_authcache=null&max_age=3600 301 Moved Permanently js_02d...ca14.js (Zeile 19)
GET http://localhost/tickets/ajax?uc_ajax_cart_authcache=null&max_age=3600 404 Not Found

As you can see from the modules js-file the ajax call is fired correctly by calling "Authcache.ajaxRequest(ajaxJason)".

authcache_custom.php looks fine, too:

function _authcache_uc_ajax_cart_authcache($vars) {
  // We need to stuff $_GET['q'] with a path that matches the securepages ignore list, otherwise
  // securepages will try to redirect us, and the ajax request will fail.
  $_GET['q'] = '/ajax/';

  // This won't work without a full bootstrap
  drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);

  require_once dirname(drupal_get_filename('module', 'uc_ajax_cart_authcache')) . '/uc_ajax_cart_authcache.module';
  return uc_ajax_cart_authcache_block_view();
}