[squid-users] using 2 parents

Dear sir/madam,

I'm using squid proxy server, and want to use 2 parent proxy.
First parent cor certain destination (based on ip address), and the second for
other destination.

I have tried to use cache_peer_access as follows, but it failed.
My squid only want to use the parent which I wrote it in upper line in my
squid.conf.

Please kindly help me to explain, how should I do it.

-- 
Regards,
Adi Nugroho
Part of my squid.conf:
cache_peer parent1 sibling 8080 3130
cache_peer parent2 sibling 3128 3130
cache_peer parent1 parent 3128 3130 no-digest no-query
cache_peer parent2 parent 3128 3130 no-digest no-query
acl iix dst "/etc/ip-iix"
cache_peer_access parent1 allow iix
cache_peer_access parent1 deny !iix
cache_peer_access parent2 allow !iix
cache_peer_access parent2 deny iix