404 error on administration page

hye guru's,

i've successfully migrate my elgg installation from development server into my production server. All functions and plugins are worked. However i facing a problem when i tried to save my site administration (url: http://mystite/pg/admin/site/). It will throw error You don't have permission to access /action/admin/site/update_basic on this server. I've change update_basic.php permission to 777 but no success.

Any ideas or solution regarding this? Thanks in advanced