In my main template I have the following:

 <%= render :partial => "delivery_date", :collection => @brand.delivery_dates, :locals => {:form => f} %>

However when the partial tries to use the form local variable, I get this error

Showing app/views/brands/_delivery_date.html.erb where line #2 raised:

wrong number of arguments (0 for 1)
Extracted source (around line #2):

1: <%= delivery_date.id %>
2: <%= form.text_field :name %>
3: <% new_or_existing = delivery_date.new_record? ? 'new' : 'existing' %>
4: <% prefix = "brand[#{new_or_existing}_delivery_date_attributes][]" %>
5: <% fields_for prefix, delivery_date do |dd_f| %>

Does anyone understand what this error means?

Actually I want to do

<% form.fields_for delivery_date do |dd_f| %> 

but that fails as well.