500 error on multipart POST, no error log

[Jonathan Vanasco]

I can't figure this out... ( nginx/0.6.31 )

my server{} block has this

     access_log  /var/log/nginx/SITE/dev.SITE.com-access.log main;
     error_log   /var/log/nginx/SITE/dev.SITE.com-error.log ;

     location ~ "^/(_img|_css|_js)" {
                 root /home/SITE/_current-web;
         }

     location ~ "^/" {
                 proxy_pass   http://127.0.0.1:5001;
         }


When trying to upload an image to the ProxyPass, I get an 500  
Internal Server Error .. but nothing goes to the error log

the access log tells me:

24.239.177.95 - jonathan [29/Jul/2008:22:11:49 +0000] 500 "POST / 
admin HTTP/1.1" 193 "http://dev.SITE.com/admin/?m=add_edit_image"  
"Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/ 
525.18 (KHTML, like Gecko) Version/3.1.2 Safari/525.22" "-" "cookie  
=cookie_val; cooki=cookie_val"

I'm probably doing something wrong , but there's no error to point me  
in the right direction.  the site works fine locally (without nginx  
proxying).  there just seems to be something on the post through  
NGINX that screws things up.