bootstrap_form error undefined method-Collection of common programming errors

1- I installed gem bootstrap_form
2- I wrote in application.css that line *= require bootstrap_form before the */ 3- in my html.erb

 student_guardians_path(@student),
html: { class: 'form-horizontal' },
method: :post) do |f| %>

And I am getting the following error : undefined methodbootstrap_form_for’ for #`

Originally posted 2013-11-09 21:38:30.