Redmine

im using postfix. in /etc/aliases i have:

shmel: "|/home/rdm-mailhandler.rb --url http://mydomain --key XXXX --project shmel --tracker new_bill_acc --allow-override tracker,priority --unknown-user accept --default-group shmel" 

when i send mail to this mailbox, in postfix log^

Mar  6 23:28:25 rt postfix/local[4362]: 899223853E: to=<shmel@mydomain>, relay=local, delay=517, delays=517/0.52/0/0.13, dsn=4.3.0, status=deferred (temporary failure. Command output: Failed to contact your Redmine server (500). )

in redmine log:

Started POST "/mail_handler" for 91.229.100.67 at Thu Mar 06 22:19:48 +0300 2014
Processing by MailHandlerController#index as HTML
  Parameters: {"no_notification"=>"", "key"=>"XXXX", "email"=>"From ab@mydomain  Thu Mar  6 23:19:48 2014\nReturn-Path: <ab@mydomain>\nX-Original-To: shmel@mydomain\nDelivered-To: shmel@mydomain\nReceived: from localhost (unknown [10.1.77.2])\n\tby mydomain (Postfix) with ESMTP id 899223853E\n\tfor <shmel@mydomain>; Thu,  6 Mar 2014 23:19:48 +0400 (MSK)\nFrom: ab@mydomain\nTo: shmel@mydomain\nReply-To: ab@mydomain\nSubject: shmel connect\nDate: Thu, 06 Mar 2014 23:19:48 +0400\nMIME-Version: 1.0\nContent-type: text/plain; charset=utf-8\nContent-transfer-encoding: 16bit\nX-Mailer: Script mailer\n\n1\n", "allow_override"=>"tracker,priority", "default_group"=>"shmel", "no_permission_check"=>"", "no_account_notice"=>"", "issue"=>{"tracker"=>"new_bill_acc", "project"=>"shmel"}, "unknown_user"=>"accept"}
Completed 500 Internal Server Error in 29.5ms

NoMethodError (undefined method `decode' for nil:NilClass):
  app/models/mail_handler.rb:46:in `receive'
  app/controllers/mail_handler_controller.rb:25:in `index'

my software:

root@pm redmine]# ruby script/about

sh: svn: command not found
sh: darcs: command not found
sh: hg: command not found
sh: bzr: command not found
Environment:
  Redmine version                2.5.0.stable
  Ruby version                   1.8.7-p357 (2011-12-28) [i686-linux]
  Rails version                  3.2.17
  Environment                    production
  Database adapter               MySQL
SCM:
  Git                            1.7.10
  Filesystem
Redmine plugins:
  no plugin installed