acl regex not working right

[Dayo Adewunmi <contactdayo@xxxxxxxxx>]

Hi guys

the following acl is supposed to deny access to any sites with the word 
"warez" in the URL.
But it's not working. What am I doing wrong?

acl warez-sites url_regex -i warez
http_access deny warez-sites

OS: Ubuntu 8.04
Squid: 2.6.18-1ubuntu3

Thanks

Dayo