You must enable the rewrite module in Apache, as the "IfModule mod_rewrite.c" states.
To do so:
- Run command-line command "a2enmod rewrite".
- Change all "AllowOverride None" lines to "AllowOverride All".
See http://www.lavluda.com/2007/07/15/how-to-enable-mod_rewrite-in-apache22-debian/.