error patch cacti-plugin-0.8.7d-PA-v2.4.diff for cacti 0.8.7

[trungtano]

Hi all!
I'm new cacti user.
I'm install cacti 0.8.7 on centOS5 it running ok until I'm patch the plugin, it doesn't work and the error is:

Forbidden

You don't have permission to access /cacti/index.php on this server.
Apache/2.2.3 (CentOS) Server at 172.24.3.30 Port 80


when i try to open my cacti page

Somebody help me?
Thanks you very much!