Make sure that you are doing all of the Custom Code steps. Save the Custom Code, create a new master .htaccess file and activate the htaccess file. If that is not the problem then…
What is probably the cause of the block is that Server Protocol HTTP/1.0 is being used and you are using the Server Protocol HTTP/1.0 spambot/hackerbot Bonus Custom Code and blocking Server Protocol HTTP/1.0 sitewide instead of just using that code for ONLY your Login page. If you are using the Bonus Custom Code in the link below then make sure that it is not being used sitewide.
http://forum.ait-pro.com/forums/topic/protect-login-page-from-brute-force-login-attacks/