Codeigniter中的自定义PHP多文件上传不起作用

$images=$_FILES['images'];
 $files_count=count($images["name"]); //get no files selected
 $allowed_ext=array("jpg",
"jpeg",
"png",
"gif",
"bmp"); // Allowed file extensions
 for($i=0;
 $i < $files_count;
 $i++) {
  $tmp=explode(".", $images["name"][$i]);
  $file_ext=strtolower(end($tmp));
  //
  if(in_array($file_ext, $allowed_ext)) {
    if($images["size"][$i] < 7340032) {
      $file_on_server=uniqid().".". $file_ext;
      //                        echo $file_on_server; exit;
      $destination=base_url()."album_images/". $file_on_server;

      if(move_uploaded_file($images["tmp_name"][$i], $destination)) {
      
        $image_data=array("album_id"=> $album_id, "name_on_server"=> $file_on_server, "filename"=> $images["name"][$i]);
        if($this->photobook->save_image($image_data)) {
          $uploaded++;  // no of files uploaded
        }
      }
      else {
        $not_uploaded++;  // no of files not uploaded
      }
    }
  }
}