[squid-users] how ccan i block aplication and media file downloading in squid

[aol]

my acl is for blocking downloading
acl dlb urlpath_regex -i \.exe$ \.mp3$ \.mov$ \.mpg$ \.mp?$ \.avi$ \.rm$
\.wma$ \.mpeg$
http_access deny dlb
but it is not working and also how can i block down loading in a time range