Script in lib that uses active records fails with `method_missing': undefined local variable or method `acts_as_taggable'

I have written a simple script in the lib directory that accesses an
active record that 'acts_as_taggable'

I get this error when I run the script.

/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.5/lib/
active_record/base.rb:1238:in `method_missing': undefined local
variable or method `acts_as_taggable' for Entity:Class (NameError)

For some reason, nothing in vendor/plugins is in the load path.
Adding the specific directories to $: doesn't help either.

Any suggestions?

Yes, I did, just tried again as well.