SMC Gateway Website blocking

I have logged in to the SMC gateway and I am using the Website Filtering to filter certain sites. I have recently tried to add Facebook to the blocked list but it is still letting traffic through.  I have tried inputting the general name "facebook" and also the www.facebook.com but neither has worked.  It is currently blocking several sites with various setups such as www.ebaumsworld.com  and "xxx".  Can someone tell me if I am not adding it correctly or is there a better way to block sites?

thanks