Served page from supercache file using PHP

Hello,

In the log that I enabled for testing WP Super Cache, I’m always getting: “Served page from supercache file using PHP”, even mod_rewrite option is enabled and my server is configuration is all okay. What can I do to get pages served by mod_rewrite, and not PHP?

Thanks.

http://wordpress.org/extend/plugins/wp-super-cache/