Redmine

Hello,
I'm moving redmine 0.9.4 (yeah that's old) from Debian Lenny to Debian Squeeze x64 and I have issues with i18n. Here are my versions:

node1:redmine# RAILS_ENV=production script/about
/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/gem_dependency.rb:119:Warning: Gem::Dependency#version_requirements is deprecated and will be removed on or after August 2010.  Use #requirement
About your application's environment
Ruby version              1.8.7 (x86_64-linux)
RubyGems version          1.3.7
Rack version              1.0
Rails version             2.3.5
Active Record version     2.3.5
Active Resource version   2.3.5
Action Mailer version     2.3.5
Active Support version    2.3.5
Application root          /srv/www/redmine
Environment               production
Database adapter          mysql
Database schema version   20100512172200

node1:redmine# gem q

*** LOCAL GEMS ***

actionmailer (3.2.9, 2.3.5)
actionpack (3.2.9, 2.3.5)
activemodel (3.2.9)
activerecord (3.2.9, 2.3.5)
activeresource (3.2.9, 2.3.5)
activesupport (3.2.9, 2.3.8, 2.3.5)
arel (3.0.2)
builder (3.0.4)
bundler (1.2.3)
daemon_controller (1.1.0)
erubis (2.7.0)
fastthread (1.0.7)
hike (1.2.1)
i18n (0.6.1, 0.5.0, 0.4.2)
journey (1.0.4)
json (1.7.6)
mail (2.4.4)
mime-types (1.19)
multi_json (1.5.0)
passenger (3.0.17)
polyglot (0.3.3)
rack (1.4.1, 1.0.1)
rack-cache (1.2)
rack-ssl (1.3.2)
rack-test (0.6.2)
rails (3.2.9, 2.3.5)
railties (3.2.9)
rake (10.0.3)
rdoc (3.12)
sprockets (2.2.2)
thor (0.16.0)
tilt (1.3.3)
treetop (1.4.12)
tzinfo (0.3.35)

I saw issues like this one: http://www.redmine.org/issues/7534. I installed i18n gem as said in the issue but I'm still having variables not replaced.

I can't upgrade to newer versions of redmine because of old custom plugins.

What can I do? How can I debug this (I'm pretty new to ruby and redmine)?

Thanks,
Michaël