how to combine this specific acl ?

Dear squid users,

In our institute I see that one specific PC in a student room is used a
lot for browsing 'nudies'. I'd like to restrict this browsing by
combining three acl's, based on:

        - the IP address/subnetmask of the PC
        - the various sites visited,
        - browsing time (disallowed between MON-FRI 09:00-17:00)

What I've tried:

        acl STUDENT_PC src x.x.x.x/255.255.255.255
        acl DIRTY_LITTLE_BASTARD dstdom_regex site1 site2 site3 site4
        acl COME_BACK_LATER MTWHF 09:00-17:00

        http_access allow STUDENT_PC
        http_access deny DIRTY_LITTLE_BASTARD
        http_access deny COME_BACK_LATER

I still get connected. Also tried:

        http_access allow COME_BACK_LATER

No difference (yes I've done a squid -k reconfigure).

Did I oversee something ?
Is what I want possible ?

Thanks for your answers.

--
Richard van Drimmelen                       | email: rdri@nki.nl
System Management Research                  | phone: +31 20 5121899
The Netherlands Cancer Institute, Amsterdam | fax:   +31 20 5121893