Updating unused field after initial creation does not work rails - ruby-on-rails-3

Question

For reference, this is using Rails 3.0.9.
I can't seem to figure out why, but I cannot update a field which was left blank at the initial creation of the object/row.
If my model looks like this:
name - string
date - date
message - string
If I put info in all of the fields upon initial creation, everything can be updated without a hitch later on. But if I do not put info in one of the fields, say the title, I cannot update that field after initial creation.
I'm not doing anything out of the ordinary, the form is pretty plain jane:
<%= form_for #event do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :name %><br />
<%= f.text_field :name %>
</p>
<p>
<%= f.label :date %><br />
<%= f.date_select :date %>
</p>
<p>
<%= f.label :message %><br />
<%= f.text_field :message %>
</p>
<p><%= f.submit %></p>
<% end %>
And my controller is equally as simple:
def update
if #event.update_attributes(params[:event])
redirect_to #event, :notice => "Successfully updated event."
else
render :action => 'edit'
end
end
And the model:
class Event < ActiveRecord::Base
has_many :races, :dependent => :destroy
has_many :price_groups, :dependent => :destroy
accepts_nested_attributes_for :races, :reject_if => lambda{ |a| a[:name].blank? }, :allow_destroy => true
accepts_nested_attributes_for :price_groups, :reject_if => lambda{ |a| a[:name].blank? }, :allow_destroy => true
attr_accessible :name, :date, :message, :races_attributes, :price_groups_attributes
end