[squid-users] Problem with ETag

[Gemmy]

 Hi~
I have a nginx webserver adding the static-etags module and a
squid2.6.23 before the nginx. When I access to the nginx directly, I can
see the ETag in response header and If-None-Match in the request header
after refresh. But when I access to the squid, ETag header still
exist,If-None-Match header disappeared!
The squid.conf have most basic configuration items, nothing about cache.
Why does this happen?