X-Accel-Redirect to proxy_pass

[Daniel]

Hi
I have 1 proxy and 2 group of web servers; the first group are the
application servers and the second group are the file storage servers
I'm trying to set the proxy in a way that the app servers send a
'X-Accel-Redirect' header with the filepath of a file in the storage
servers without luck.

the app server send the header:
down.php
<?php
header('X-Accel-Redirect: /store/data/mass4.txt');
?>

the conf in the proxy is:
location /store/ {
internal;
proxy_pass http://filestore;
}

the filestore server error log

192.168.1.9 - - [12/Aug/2008:23:03:56 +0900] "GET /tst/down.php
HTTP/1.0" 404 169 "http://proxyserver/tst/" "Mozilla/5.0 (X11; U; Linux
i686; ja; rv:1.9.0.1) Gecko/2008072820 Firefox/3.0.1"


Is there a way to use X-Accel-Redirect with 3 servers or the files to
download have to be in the proxy server?.

nginx version: nginx/0.6.32

Regards

Tuqui