Observer + acts_as_taggable plugin = dead app

so i have found that if i try to place an observer on a model that is
using the acts_as_taggable plugin, my app will not start up. this is
what i get in the mongrel startup log

/Applications/Locomotive2/Bundles/rmagickRailsSept2006_ppc.locobundle/framework/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/base.rb:1129:in
`method_missing': undefined local variable or method `acts_as_taggable'
for Profile:Class (NameError)

if i comment out either the observer in the config/environment.rb or
the acts_as_taggable it starts up fine.

any help would me majorly appreciated