Proxy issue

I’m trying to set up a transparent proxy in order to deny clien’t access to some sites. It seems, that i’m doing everything fine, but the proxy does not work: the pings go thru without any problem, however all the browser requests wait for response for a minute (or something around it) and than return a blank page.
Here is my config:

Proxy:

[admin@MikroTik] > /ip proxy print
                 enabled: yes
             src-address: 0.0.0.0
                    port: 8080
            parent-proxy: 0.0.0.0
       parent-proxy-port: 0
     cache-administrator: "mymailhere"
          max-cache-size: 10000KiB
           cache-on-disk: no
  max-client-connections: 600
  max-server-connections: 600
          max-fresh-time: 3d
   serialize-connections: no
       always-from-cache: no
          cache-hit-dscp: 4
             cache-drive: secondary-master

NAT rule:

15 X ;;; Proxy
     chain=dstnat action=redirect to-ports=8080 protocol=tcp 
     src-address=10.1.1.0/24 dst-port=80

I have PPPoE set up on my user’s computers to allow bandwith accounting for several users on the machine, however i’ve tried switching it off - did not help =(

Any ideas?
Thx in advance.

/ip proxy monitor once ?

Here it goes:

[admin@MikroTik] > /ip proxy monitor 
                 status: running
                 uptime: 22h58m20s
               requests: 140
                   hits: 0
             cache-used: 0KiB
         total-ram-used: 143KiB
  received-from-servers: 126KiB
        sent-to-clients: 156KiB
   hits-sent-to-clients: 0KiB

/ip firewall nat add chain=srcnat out-interface=your_uplink action=masquerade

seems that it did not help =( still the same =(