Short answer: are there any error logs of havp? You also should make squid exceptions for https requests, because havp can't scan ssl connections!
What squid version are you using? Following is an example sandwich configuration for squid
Code:
http_port 192.168.1.1:3128 transparent
# Needed if using sandwich configuration
http_port 127.0.0.1:3129
# Define acl for HAVP port (the port HAVP connects to SQUID2)
acl FROM_HAVP myport 3129
# Don't log duplicate requests coming from HAVP
log_access deny FROM_HAVP
# HAVP on localhost port 8001
cache_peer 127.0.0.1 parent 8001 0 name=havp proxy-only no-query no-digest no-netdb-exchange default
# Needed if we want to go directly to SQUID2 without HAVP
cache_peer 127.0.0.1 parent 3129 0 name=squid2 proxy-only no-query no-digest no-netdb-exchange
# This makes sure ALL requests are sent to parent peers when needed
prefer_direct off
nonhierarchical_direct off
# HTTPS traffic scanning not needed
# (squid2 skipped too, since it can't be cached)
acl HTTPS proto HTTPS
acl SSL proto SSL
always_direct allow SSL
# Always force use of HAVP or Squid2 parent
never_direct allow !FROM_HAVP
# It's easier to create whitelists her than in HAVP
# Also, if there is a bug in HAVP, whitelisting there might not work (please uncomment and modify)
#acl NOSCAN dstdomain .some_domain.com
cache_peer_access havp deny FROM_HAVP
cache_peer_access havp deny SSL
cache_peer_access havp deny NOSCAN
cache_peer_access havp allow all
cache_peer_access squid2 deny FROM_HAVP
cache_peer_access squid2 allow all
This example should work too, if deleting all squid2 entries.