502 грешка nginx + ruby ​​on rails приложение

Подробности за приложението:
Rails 3.1.0
Ruby 1.9.2
unicorn 4.2.0
resque 1.20.0
nginx/1.0.14
redis 2.4.8

Използвам active_admin gem, за всички URL получаващи отговор 200,
но само един URL дава грешка 502 при производство.

рейк маршрути:

admin_links GET        /admin/links(.:format)                                            {:action=>"index", :controller=>"admin/links"}

И работи върху местно (развитие).

log на локален хост: код на отговор 200

    Started GET "/admin/links" for 127.0.0.1 at 2013-02-12 11:05:21 +0530
        Processing by Admin::LinksController#index as */*
        Parameters: {"link"=>{}}
    Geokit is using the domain: localhost
        AdminUser Load (0.2ms)  SELECT `admin_users`.* FROM `admin_users` WHERE `admin_users`.`id` = 3 LIMIT 1
         (0.1ms)  SELECT 1 FROM `links` LIMIT 1 OFFSET 0
         (0.1ms)  SELECT COUNT(*) FROM `links` 
         (0.2ms)  SELECT COUNT(count_column) FROM (SELECT 1 AS count_column FROM `links` LIMIT 10 OFFSET 0) subquery_for_count 
        CACHE (0.0ms)  SELECT COUNT(count_column) FROM (SELECT 1 AS count_column FROM `links` LIMIT 10 OFFSET 0) subquery_for_count 
        Link Load (0.6ms)  SELECT `links`.* FROM `links` ORDER BY `links`.`id` desc LIMIT 10 OFFSET 0
        Link Load (6677.2ms)  SELECT `links`.* FROM `links` 
    Rendered /usr/local/rvm/gems/ruby-1.9.2-head/gems/activeadmin-0.4.2/app/views/active_admin/resource/index.html.arb (14919.0ms)
    Completed 200 OK in 15663ms (Views: 8835.0ms | ActiveRecord: 6682.8ms | Solr: 0.0ms)

производствен дневник: 502 отговор

    Started GET "/admin/links" for 103.9.12.66 at 2013-02-12 05:25:37 +0000
        Processing by Admin::LinksController#index as */*
        Parameters: {"link"=>{}}

Регистър на грешките на NGinx

2013/02/12 07:36:16 [error] 32401#0: *1948 upstream prematurely closed connection while reading response header from upstream

не знам какво се случва, може ли някой приятел да ми помогне.