Apache2.2 : AuthUserFile Error

<Location /svn>
       DAV svn
       SVNParentPath "/var/svn"
       AuthzSVNaccessFile /var/svn/.htpasswd
       AuthType Basic
       AUthName "Dev Project"
       AuthUserFile /var/svn/.htpasswd
</Location>

I set the basic authentication such as above which ended up the below error.

# /etc/init.d/apache2 reload
Syntax error on line 64 of /etc/apache2/mods-enabled/dav_svn.conf:
Invalid command 'AuthUserFile', perhaps misspelled or defined by a module not included in the server configuration

Since below,

$ for i in /usr/lib/apache2/modules/*; do strings $i | grep -q -i AuthUser && echo $i; done
/usr/lib/apache2/modules/mod_authn_file.so
$ ls /etc/apache2/mods-available/authn_file.load
/etc/apache2/mods-available/authn_file.load

You need to do as follow,

$ sudo /usr/sbin/a2enmod authn_file
Module authn_file installed; run /etc/init.d/apache2 force-reload to enable.
$ /usr/sbin/apache2ctl configtest
Syntax OK