Forwarding third domain url to directory in the main domain

Hullo, I would like to forward accesses to subdomain blog.xxx.yy to directory www.xxx.yy/blog possibly keeping the originary address in the address field of the browser. How may I do it? I tried with:

Code:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^blog\.taxiprofessional\.net
RewriteRule ^([0-9]+)/?$ blog [NC,L]

but it does not work.

 

I forgot to enable the .htaccess reading in the httpd.conf file.