Help with recursive function

Hello again; I am writing a recursive file system reading method (just for the challenge, i am re inventing a wheel) and I am only getting to the third level below the initial dir when I know there is five levels below. I don't see why: private function getDirList($_dir)

               {
                $_out = array();
                $_valid = '';
                $_DR = opendir($_dir);
                while($_x = readdir($_DR))
                  {
                   switch($_x)
                     {
                      case '.':
                      case '..':
                      break;
                      default:
                      if(is_dir($_x))
                        {
                         $_valid = self::screen($_dir.'/'.$_x, 'dir');
                         if($_valid['error'])
                           {
                            self::$_readError[count(self::$_readError)] = $_valid['error'];
                            continue;
                           }
                         else if($_valid['pass'])
                           {
                            self::$_dirsToRead[$_dir.'/'.$_x] = true;
                            self::getDirList($_dir.'/'.$_x); ///<<<< this should accumulate directories, shouldn't it?
                           }
                        }
                      else if(is_file)
                        {
                         continue;
                        }
                      break;
                     }
                  }
                closedir($_DR);
               }

thank you for time and attention JK