PHP 递归迭代器迭代器:系统找不到指定的路径

当我想用RecursiveIteratorIterator和spl_autoload_register自动加载类时，我遇到了此错误，

未捕获的异常"意外值异常"与消息 'RecursiveDirectoryIterator：：__construct（）：系统找不到 指定的路径。（代码：3）

什么意思？

下面是我的类自动加载器，

function autoload_multiple_directory($class_name){
    // List all the class directories in the array.
    $array_directories = array(
        'core/controller/', 
        'core/model/',
        'core/helper/',
        'core/ext/'
    );
    $parts = explode('''', $class_name);
    // Set the class file name.
    $file_name = end($parts).'.php';
    foreach($array_directories as $path_directory){
        $iterator = new RecursiveIteratorIterator(
            new RecursiveDirectoryIterator($path_directory),
            RecursiveIteratorIterator::SELF_FIRST
        );
        foreach ($iterator as $fileObject) {
            if ($fileObject->isDir()) {
                $files[] = str_replace('''', '/', $fileObject->getPathname()).'/';
            }
        }

    }

    $array_directories = array_merge($array_directories,$files);
    // Loop the array.
    foreach($array_directories as $path_directory){
        if(file_exists(WEBSITE_DOCROOT.$path_directory.$file_name)){
            include WEBSITE_DOCROOT.$path_directory.$file_name;
        } 
    }
}

spl_autoload_register('autoload_multiple_directory');

错误线指向new RecursiveDirectoryIterator($path_directory),为什么？