Deeply Nested Form Data not going into database, no errors - ruby-on-rails

Question

I'm building a multi-nested form in rails 3. I'm using the formtastic_cocoon gem, but I don't think that has much bearing on this issue.
I've got users, users have tasks, tasks have steps.
The nesting is users>tasks>steps.
I can dynamically add and remove the task fields to the user, and the step fields from the tasks.
However, when I submit the form, the user gets tasks, but the task>steps don't get saved to the database.
Rails isn't returning any errors, just nothing happens.
My models are
Class User < ActiveRecord::Base
acts_as_authentic
has_many :tasks
accepts_nested_attributes_for :tasks, :reject_if=> proc {|attributes| attributes[:entry].blank?}, :allow_destroy => true
end
Class Task < ActiveRecord::Base
attr_accessible :entry
belongs_to :user
has_many :steps
accepts_nested_attributes_for :steps, :reject_if=> proc {|attributes| attributes[:title].blank?}, :allow_destroy => true
end
Class Step < ActiveRecord::Base
attr_accesible :title
belongs_to :task
end
In my form.html.erb I have
<%= semantic_form_for #user %>
<%= form.inputs :username, :password %>
<div>
<% form.semantic_form_fields_for :tasks do |builder| %>
<%= render 'task_fields', :f=>builder %>
<% end %>
<%= link_to_add_association 'add task', form, :tasks %>
</div>
The _task_fields.html.erb looks like this
<div class="nested-fields">
<%= link_to_remove_association "remove task", f %>
<%= f.inputs :entry %>
<div>
<% f.semantic_form_fields_form :steps do |builder| %>
<%= render 'step_fields' :f => builder %>
<% end %>
<%= link_to_add_association 'add step', f, :steps %>
</div>
</div>
lastly, the _step_fields.html.erb page is
<div class="nested-fields">
<%= link_to_remove_association "remove step", f %>
<%= f.inputs :title %>
</div>

Answer 1

Do you see this in the log?:
WARNING: Can't mass-assign protected attributes: steps_attributes
If so, add this to the Task model:
attr_accessible :steps_attributes