Apache的; 命令'DavLockDB'无效

Just learning about PHP and MySQL. Attempting to enable PHP on Mac Mini. I've followed several thread regarding this, but have not found a solution.

Terminal Output:

Jessicas-Mac-mini:~ jessicaclark$ php -v
PHP 5.5.14 (cli) (built: Sep  9 2014 19:09:25) 
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
Jessicas-Mac-mini:~ jessicaclark$ cd /etc/apache2/
Jessicas-Mac-mini:apache2 jessicaclark$ sudo nano httpd.conf
Password:
Jessicas-Mac-mini:apache2 jessicaclark$ sudo apachectl restart
Password:
Jessicas-Mac-mini:apache2 jessicaclark$ httpd -v
Server version: Apache/2.4.9 (Unix)
Server built:   Sep  9 2014 14:48:20
Jessicas-Mac-mini:apache2 jessicaclark$ apachectl configtest
AH00526: Syntax error on line 15 of /private/etc/apache2/extra/httpd-dav.conf:
Invalid command 'DavLockDB', perhaps misspelled or defined by a module not included in the server configuration

Supposed to be able to open http://localhost/ with 'It works!'...Any feedback appreciated!