Forum: Rails I18n gettext 1.90 to 2.0.5

I upgrade our project from Rails 2.0.2 to Rails 2.3.5. We are using
gettext 1.9x, so I follow this tutorial to upgrade the gettext plugin.:
http://www.yotabanana.com/hiki/ruby-gettext-rails-...

base on the following tutorial, we use before_filter and set_locale in
application controller:
http://www.yotabanana.com/hiki/ruby-gettext-howto-...
however it does not work.

The first time the user set the locale, the page works, however when the
user go to other page, the locale setting either rollback or override by
user's browser settings.

I also tried I18n.locale and GetText.locale to set the locale, it
doesn't help.

Any idea what is gonig on in my case?

Thanks.

the gettext, gettext_activerecord, gettext_rails is version 2.1.0