BotTracker doesn't create the Database Tables

Hi, i ran into the Problem that BotTracker doesn’t create the Database Tables bot_DB*.

Latest Piwik 2.15, BotTracker Installation from Webinterface without any issues.

If i try to open /piwik/plugins/BotTracker/BotTracker.php i got

PHP Fatal error: require_once(): Failed opening required ‘PIWIK_INCLUDE_PATH/plugins/BotTracker/functions.php’ (include_path=’.:/usr/share/pear:/usr/share/php’) in /var/www/html/piwik/plugins/BotTracker/BotTracker.php on line 24

die(PIWIK_INCLUDE_PATH); --> “/var/www/html/piwik” , but only on index.php, not on BotTracker.php, there i got “PIWIK_INCLUDE_PATH”

Apache/2.2.15, PHP 5.4.45 Default Installations

Any hints?