Rails 3.0 and form_for

I am having trouble displaying form_for in my rails 3 app that i upgraded from a 2.3.8. i realize taht you are suppose to change all of the <% to <%=. However, despite that i am getting no output. it is as if the form_for does not exist. I have not tested all of the form_for's but i can not get any of the ones i have tried so far.

any other obvious that needs to be changed?

Hi, this link explains how to create forms in ror (Crear formulario en Rails on Vimeo).