No keep-alives in connections cache<->servers?

While checking some of Squid's statistics thru' cachemgr.cgi, I noticed 
that Squid reports "keep-alive ratio: 0%" for all my parents.

I checked FAQ for it: "This is a mechanism to try detecting neighbor 
caches which might not be able to deal with HTTP/1.1 persistent 
connections". This is very interesting, because my parents DO support 
keep-alive (with both HTTP/1.0 and 1.1). I even checked it with 
telnetting parents and manually tested by typing headers etc.

I have next settings in my squid.conf regarding to persistent connections:
    client_persistent_connections on
    server_persistent_connections on
    pipeline_prefetch on

Then I checked with packet sniffer that is Squid even sending those 
"Connection: keep-alive" -headers to servers - but no.

Is there some kind of special way to enable keep-alives here? I tried to 
understand the logic in sending those or not from source, but it would 
take more time than I'm able to spend now.


Regards,
--
Pauli Borodulin
boro@xxxxxxxxx