Strange error message when rendering the scaffold form

Hello everyone, I am developing my application and I created a scaffold called listas, but when I acess /listas/new I get this error message:

NoMethodError in Listas#new

Showing /home/rodrigo3n/code/listeiroo/app/views/listas/_form.html.erb where line #15 raised:

undefined method `deep_symbolize_keys' for nil:NilClass Extracted source (around line #15):

12: <% end %> 13: 14: <div class="field"> 15: <%= f.label :nome %><br /> 16: <%= f.text_field :nome %> 17: </div> 18: <div class="field"> Trace of template inclusion: app/views/listas/new.html.erb

I am using Rails 3RC and Ruby 1.9.2-rc2. This error is very strange to me because I did just create the scaffold via "% rails g scaffold" and then this error appeared. Do you know why?

Thanks, Rodrigo Alves Vieira

Did you migrate the database?