Limiting access to bad URLs

[Vittorio <vdemart@supereva.it>]

Under woody I've setup a small server using Squid proxy and diald.

Now, because the Internet will be used by children I don't want them to access pornographic material so in squid.conf I put the following (some words are in Italian):

#SQUID.CONF begins exactly here
http_port 8080
#We recommend you to use the following two lines.
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY
#DO NOT ENTER 
acl niet1 url_regex -i sex
acl niet2 url_regex -i sesso
acl niet3 url_regex -i porn

http_access deny niet1
http_access deny niet2
http_access deny niet3
<SNIP>

I have tried with two Italian porno sites where in the urls are present
the words "sesso" and "porno" but nothing prevented squid from loading them.

Why?

Could you please suggest a well-formed squid.conf to this aim?

Vittorio