Rails fields_for form not showing up, nested form

I have created an simple rails project. All worked fine until I tried to add a new model `Paintings` that `belongs_to` treatment and an `Patient` that `has_many` Paintings through Treatment. So somehow the nested form I created does not show up, I believe it has to do with the controller! Thanks, and greetings from Germany! Treatments controller: ``` class TreatmentsController < ApplicationController def create @patient = Patient.find(params[:patient_id]) @treatment = @patient.treatments.create(params[:treatment]) redirect_to patient_path(@patient) end def destroy @patient = Patient.find(params[:patient_id]) @treatment = @patient.treatments.find(params[:id]) @treatment.destroy redirect_to patient_path(@patient) end end ``` And the form for treatments with `nested fields_for` that doesn't show up: ``` <%= form_for([@patient, @patient.treatments.build]) do |f| %> <div class="field"> <%= f.label :content %> <%= f.text_area :content, :cols => "30", :rows => "10" %> </div> <div class="field"> <%= f.label :category_id %> <%= f.collection_select :category_id, Category.find(:all), :id, :typ %> </div> <%= f.fields_for :paintings do |ff| %> <div class="field"> <%= ff.label :name, 'Tag:' %> <%= ff.text_field :name %> </div> <% end %> <div class="field"> <%= f.submit nil, :class => 'btn btn-small btn-primary' %> </div> <% end %> ``` UPDATE: Show Site: ``` <% @patient.treatments.each do |treatment| %> <tr> <td><%= treatment.category.try(:typ) %></td> <td><%= treatment.content %></td> <td><%= treatment.day %></td> <td><div class="arrow"></div></td> </tr> <tr> ```