Acts_as_dropdown: NoMethodError on load

Rails 1.1.6 on gems
I had the acts_as_dropdown plugin working fine, but now starting webrick
gives me a:
C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/base.rb:1129:in
method_missing': undefined methodacts_as_dropdown’ for User:Class (NoMethodError)

My other plugins are working fine.

I have the latest version of acts_as_dropdown.
Gems are up to date.

It works in the console! If I do User.to_dropdown, I get the expected
output.
It works okay for other classes with acts_as_dropdown, too. Just this
one
class has issues.

Any guidance appreciated, especially if I’m overlooking something
obvious.

-- Wes