Some ZF classes load user-defined classes (such as Zend_Db_Table_Abstract::fetchRow()) with Zend_Locale::loadClass(). However, the loadClass() method will not work if the user-defined class is not in the PHP's include_path and/or has an application-specific prefix. User-defined autoloaders would work, but Zend_Locale::loadClass() doesn't use them, even if it couldn't load the requested class. Zend_Locale::loadClass() should use a third optional parameter, $tryUserAutoloaders = false, for this method to try loading the requested class with user-defined autoloaders if it itself couldn't load the requested class. I'm going to fix this because I need it for my code to work.