安装django内置comments评论系统出错，求解答！！

[click]

完全按照官方的方法做，
第一步，在 settings 文件中，INSTALLED_APPS 项添加 'django.contrib.comments', 这步没问题

但第二步python manage.py syncdb时系统提示错误：
CommandError: One or more models did not validate:
comments.comment: 'site' has a relation with model <class 'django.contrib.sites.
models.Site'>, which has either not been installed or is abstract.

求解答！！

[mozillazg]

INSTALLED_APPS 追加 'django.contrib.sites'