WCF::handleException() Unhandled exception: Argument 1 passed to wcf\system\menu\page\PageMenu::checkMenuItem() must implement interface wcf\system\menu\ITreeMenuItem, instance of __PHP_Incomplete_Class given, called in /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/menu/TreeMenu.class.php on line 113

#0 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/menu/TreeMenu.class.php(113): wcf\system\menu\page\PageMenu->checkMenuItem(Object(__PHP_Incomplete_Class))
#1 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/menu/page/PageMenu.class.php(34): wcf\system\menu\TreeMenu->checkMenuItems('header')
#2 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/SingletonFactory.class.php(27): wcf\system\menu\page\PageMenu->init()
#3 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/SingletonFactory.class.php(56): wcf\system\SingletonFactory->__construct()
#4 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/request/RequestHandler.class.php(122): wcf\system\SingletonFactory::getInstance()
#5 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/lib/system/request/RequestHandler.class.php(87): wcf\system\request\RequestHandler->buildRequest('wbb')
#6 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/index.php(10): wcf\system\request\RequestHandler->handle('wbb')
#7 {main}