SSL login not working, and a possibly related error message

I just tried to enable SSL for logins, and it’s not working (URL still appears as non-SSL when login prompt is displayed). I don’t know whether it’s related or not, but the following error message appears on the plugin control panel:

Fatal error: Call to undefined method WP_Error::get_items() in /Users/gpetty/Sites/wp/wp-content/plugins/better-wp-security/lib/bit51/bit51.php on line 353

I was using Better WP Security 3.4.9 and WordPress 3.5; I just upgraded the plug-in to 3.4.10. The error message is not showing now, but the login is still non-SSL.