Bitnami Cloud, Ubuntu > VirtualDocumentRoot command not found

I'm attempting to enable mass virtual hosting, per http://httpd.apache.org/docs/current/mod/mod_vhost_alias.html

IN FILE :

/opt/bitnami/apache2/conf/httpd.conf

I'M ADDING LINES :

UseCanonicalName Off

VirtualDocumentRoot /opt/bitnami/apache2/htdocs/%-2/%0/www/

I've done the prerequisite :

sudo a2enmod vhost_alias

I've tried everything in the book to get the server to recognize VirtualDocumentRoot. No luck.

I've done this on other Ubuntu AMIs without problems.

Am I missing a module install somewhere??