"Firewall(?)" blocks "Accept-Encoding" header

recently, I did Gzip testing with loadrunner with "Accept-Encoding: gzip, deflate" request headers, so want to make sure that Gzip rocks as i told to my teammates.

My test scenario is running from remote server which located in US DC, it sent requests to China servers.

However, i noticed the test result is not changed, then i doubt about Gzip impact, keep look at apache access logs by adding \"%{Accept-Encoding}i\" to LogFormat in httpd.conf. There is no "gzip, deflate" header in access log found:

"GET / HTTP/1.1" 200 2788 0 "-" "Mozilla/5.0 (compatible; MSIE 6.0; Windows NT 5.1)" "-"

Then I did another round of test from local desktop, then everything is fine:

"GET / HTTP/1.1" 200 2788 0 "-" "Mozilla/5.0 (compatible; MSIE 6.0; Windows NT 5.1)" "gzip, deflate"

So "Firewall" blocks "Accept-Encoding" header is just my assumption, but not quite sure... At least notice your test result is making sense, otherwise, you are wasting of time, do not let such test result misleading!

Update:
Find a person with similar issue as mine: http://forums.mozillazine.org/viewtopic.php?f=9&t=1483185
There is Outpost Firewall which disable gzip...

Another latest post on "pushing beyond Gzipping" by Yahoo! talking about forcing Gzip when Accept-Encoding request header is mangled or stripped.