How to use AliasMatch with Apache 2?

I have a site with virtual hosts and I need to do the following:

when someone types this:
http://www.mydomain.com/stats

where mydomain is the virtual domain

Apache has to redirect the files to
/HTMLRoot/stats/www.mydomain.com

The normal documentroot is
/HTMLRoot/htdocs/www.mydomain.com

I think I can do this by adding this to httpd.conf:
AliasMatch ^/stats(.*) /HTMLRoot/stats/$1
<Directory /HTMLRoot/stats/>
Options FollowSymLinks
AllowOverride None
Order allow,deny
Allow from all
</Directory>

but it doesn't work... What am I doing wrong?