diff --git a/lib/Kolab/CalDAV/SchedulePlugin.php b/lib/Kolab/CalDAV/SchedulePlugin.php
index 9ea278f..7500084 100644
--- a/lib/Kolab/CalDAV/SchedulePlugin.php
+++ b/lib/Kolab/CalDAV/SchedulePlugin.php
@@ -1,101 +1,103 @@
 <?php
 
 /**
  * Extended CalDAV Schedule plugin for the Kolab DAV server
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2014, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 namespace Kolab\CalDAV;
 
 use Sabre\DAV;
 use Sabre\CalDAV;
 use Sabre\VObject;
 use Sabre\HTTP;
+use Kolab\DAV\Auth\HTTPBasic;
+
 
 /**
  * Extended CalDAV Schedule plugin
  */
 class SchedulePlugin extends CalDAV\Schedule\Plugin
 {
     /**
      * Returns free-busy information for a specific address. The returned
      * data is an array containing the following properties:
      *
      * calendar-data : A VFREEBUSY VObject
      * request-status : an iTip status code.
      * href: The principal's email address, as requested
      *
      * @param string $email address
      * @param \DateTime $start
      * @param \DateTime $end
      * @param VObject\Component $request
      * @return array
      */
     protected function getFreeBusyForEmail($email, \DateTime $start, \DateTime $end, VObject\Component $request)
     {
         console(__METHOD__, $email, $start, $end);
 
         $email = preg_replace('!^mailto:!i', '', $email);
 
         // pass-through the pre-generatd free/busy feed from Kolab's free/busy service
         if ($fburl = \kolab_storage::get_freebusy_url($email, $start, $end)) {
             try {
                 $rcube = \rcube::get_instance();
                 $client = new HTTP\Client();
                 $client->addCurlSetting(CURLOPT_SSL_VERIFYPEER, $rcube->config->get('kolab_ssl_verify_peer', true));
 
                 // authentication required
                 $client->on('error:401', function($request, $response, &$retry, $retryCount) {
                     if ($retryCount <= 1) {
                         // We're only going to retry exactly once.
                         $request->setHeader('Authorization', 'Basic ' . base64_encode(HTTPBasic::$current_user . ':' . HTTPBasic::$current_pass));
                         $retry = true;
                     }
                 });
 
                 $response = $client->send(new HTTP\Request('GET', $fburl));
 
                 // success!
                 if ($response->getStatus() == 200) {
                     $vcalendar = VObject\Reader::read($response->getBodyAsString(), VObject\Reader::OPTION_FORGIVING | VObject\Reader::OPTION_IGNORE_INVALID_LINES);
                     $vcalendar->METHOD = 'REPLY';
                     return array(
                         'calendar-data' => $vcalendar,
                         'request-status' => '2.0;Success',
                         'href' => 'mailto:' . $email,
                     );
                 }
             }
             catch (\Exception $e) {
                 // log failures
                 \rcube::raise_error($e, true, false);
             }
         }
         else {
             // generate free/busy data from this user's calendars
             return parent::getFreeBusyForEmail($email, $start, $end, $request);
         }
 
         // return "not found"
         return array(
             'request-status' => '3.7;Could not find principal',
             'href' => 'mailto:' . $email,
         );
     }
 }
\ No newline at end of file