RSPEC and Custom Validation date fields

HI All, I have a model that uses custom validation. The validation works from the browser but RSPEC gives it an error. It looks to me like RSPEC isn't seeing the start_time and end_time fields in my model. If I change line 9 in my validation to something like "unless title == title" I don't have any problem. The issues seems to be with date fields. I suspect this is a bug but since I'm new to RSPEC I'd like advice before reporting it.

Here is the error from rspec:

    You have a nil object when you didn't expect it!     The error occurred while evaluating nil.<

    /home/leo/railsprojects/trunk/memorymap/app/models/event.rb:9:in `valid_dates?'     /home/leo/railsprojects/trunk/memorymap/spec/models/event_spec.rb: 24:

    7     8 def valid_dates?     9 unless start_time < end_time     10 errors.add("End Time must be later than Start Time")     11 end

Here is my model:

1 class Event < ActiveRecord::Base   2 validates_presence_of :title, :description, :start_time, :end_time   3 validates_uniqueness_of :title   4 validate_on_create :valid_dates?   5   6 private   7   8 def valid_dates?   9 unless start_time < end_time 10 errors.add("End Time must be later than Start Time") 11 end 12 end 13 end