# File lib/pluginfactory.rb, line 308
        def load_derivative( class_name )
                PluginFactory.log.debug "Loading derivative #{class_name}"

                # Get the unique part of the derived class name and try to
                # load it from one of the derivative subdirs, if there are
                # any.
                mod_name = self.get_module_name( class_name )
                result = self.require_derivative( mod_name )

                # Check to see if the specified listener is now loaded. If it
                # is not, raise an error to that effect.
                unless self.derivatives[ class_name.downcase ]
                        errmsg = "Require of '%s' succeeded, but didn't load a %s named '%s' for some reason." % [
                                result,
                                self.factory_type,
                                class_name.downcase,
                        ]
                        PluginFactory.log.error( errmsg )
                        raise FactoryError, errmsg, caller(3)
                end
        end