nginx proxy zope/webdav, can´t see files

[mictlan tecutli]

hi,
i´m trying to use nginx to proxy to the zope webdav interface. i´m using davfs2 for webdav client. and it works well when i connect directly to the zope/webdav server. but when i proxy using nginx something strange occurs. i can not see the files using my webdav client. i can upload files if i connect directly to the folder where i have permissions to put them. but if i try to list files in the davfs mountpoint, nothing is shown. niether files nor folders. 

the proxy part of my virtualhost looks like this:

                            location /dav/ {
                                proxy_pass http://10.10.10.30:1980/plone/;
                                proxy_set_header Host $host;
                                proxy_set_header  X-Real-IP  $remote_addr;
                                proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
                                proxy_redirect   off;
                                }

as i understand it nginx when in proxy mode passes data unchanged. so what would account for the difference between connecting directly and by way of nginx?

zope http logs of the interaction look like this:
10.10.10.20 - Anonymous [09/Dec/2008:21:03:12 -0500] "OPTIONS /plone/ HTTP/1.0" 200 346 "" "davfs2/1.3.3 neon/0.28.2"
10.10.10.20 - Anonymous [09/Dec/2008:21:03:15 -0500] "PROPFIND /plone/ HTTP/1.0" 401 11557 "" "davfs2/1.3.3 neon/0.28.2"
10.10.10.20 - radracer [09/Dec/2008:21:03:25 -0500] "PROPFIND /plone/ HTTP/1.0" 207 11784 "" "davfs2/1.3.3 neon/0.28.2"
10.10.10.20 - radracer [09/Dec/2008:21:05:47 -0500] "PROPFIND /plone/ HTTP/1.0" 207 11784 "" "davfs2/1.3.3 neon/0.28.2"

i´ve attached some davfs2 http debugging info in case thats helpful.

nginx version is 0.6.34. i´ve also tried with 0.5.35 and 0.4.13

thanks for any help, 
kev
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