Unable to get HTTPS to Work

I have no doubt the error is mine, but I am stuck. =)

I have read the installation and FAQs multiple times, but every time I enable the feature I can no longer access it via admin login.

I am trying to secure admin for a site in a subdirectory of my primary site.
The sites are being served from hostgator.

Site: http://www.heritagelearning.org

I would appreciate any instruction/suggestions you could make,

Thanks, Mike

http://wordpress.org/extend/plugins/wordpress-https/