acts_as_taggable

Hi, i was trying the acts_as_taggable gem, without success

i've installed the gem (gem install acts_as_taggable),
added "gem 'acts_as_taggable'" at the end of environment.rb,
and added 'acts_as_taggable' into my Artigo model

but when i try to use my model now, i get this error message:
NoMethodError: undefined method `acts_as_taggable' for Artigo:Class

any ideas?
thanks,
Paulo Geyer

Did you restart your server? It's required after modifying environment.rb.

Yes, i've restarted my server, as it seems, acts_as_taggable was
loaded without problems.
I did an test adding "gem 'foo'" to see if i get an error message, and
i got. So it is there

i'm still trying to figure out what is happening here, if you have any
other suggestions, please tell me

thanks