Cache on MK 3.22

Hi Every One

I have MK V3.22 and I setup web-proxy step by step for cache.
The web-proxy status now is running, But the cache is not working
I down load one file 32Mb then I close the browser
I open the browser again and download the same file from the same site,
But it download from internet with internet download speed ( not from cache )

My Firewall Nat is:-
[admin@MOWM] /ip firewall nat> print
Flags: X - disabled, I - invalid, D - dynamic
0 chain=srcnat action=masquerade out-interface=!Internal
1 chain=dstnat action=redirect to-ports=8080 protocol=tcp
in-interface=External dst-port=80
2 chain=dstnat action=redirect to-ports=8080 protocol=tcp dst-port=80
[admin@MOWM] /ip firewall nat>

And My web-proxy is:-
[admin@MOWM] /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: “This Site Is Blocked Call 400”
max-cache-size: 80000000KiB
cache-on-disk: yes
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: primary-master
[admin@MOWM] /ip proxy>

Where is the error

Can Any One Help
Thanks