How to enable mod_rewrite in apache on Ubuntu

Try putting the rewrite rules directly into the VirtualHost config section (not under a "Directory" rule)

This way you can bypass any problems that may be cause by .htaccess and path identification mechanisms.

Check if rewrite_module is loaded into apache:

apache2ctl -t -D DUMP_MODULES

If not enabled, enable the mod_rewrite with

a2enmod rewrite

This will set up necessary links under mods-enabled (not mods-available)

I notice that in your rewrite rule, the pattern to match ends with a slash, but the URL you accessed didn't. Try removing the slash from http-poll/ in the RewriteRule and see if that makes it work.