gzip compression not taken into account?

[jfix]

Hi, I have enabled gzip compression following the wiki instructions like
this:

location / {
 #....

 gzip on;
 gzip_min_length 1000;
 gzip_proxied expired no-cache no-store private auth;
 gzip_types text/plain application/xml text/javascript text/css
application/x-javascript;
 gzip_disable "MSIE [1-6]\.";
 
 #...
}

unfortunately, both Yahoo's yslow and Google's pagespeed tell me that I
should enable compression for better performance. 

How can I find out why compression doesn't seem to happen?  I've
selected the mime-types after having looked at them in chrome's web
inspector.

Thank you in advance,
Jakob.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,197898,197898#msg-197898