[squid-users] No_cache directive

I have a RH 7.2 (2.4.17) running squid (2.4 - STABLE 4). I'm triying to
block
serveral files caching with the no_cache tag :

acl FICHEROS urlpath_regex \.xml$ \.css$ \.jar$ \.dtd$
no_cache deny FICHEROS

... but in the access log I can see that css and dtd files are being cached:

orfeo - - [28/Feb/2002:17:02:34 +0100] "GET
http://xxxxx.servicios_un.dtd HTTP/1.0" 200 3607 TCP_HIT:NONE
orfeo - - [28/Feb/2002:17:02:34 +0100] "GET http://xxxxx.servicios.css
HTTP/1.0" 200 6848 TCP_HIT:NONE

I'm doing something wrong ? Can I do anything to avoid caching those files ?

Thanks in advance, Ignacio Bernal