Can't login

I go to my login page and I get the following error:

Fatal error: Call to undefined function force_ssl_admin() in /home/tswelti1/public_html/blog/wp-login.php on line 15

This is what I see in Line 15 of the wp-login.php file:

if ( force_ssl_admin() && !is_ssl() ) {

What is causing the error and how do I fix it? I don’t understand it.

Thanks. 🙂