customized form_for in ApplicationHelper


I want to make a table within a form by making a new form_tag. The
following code in ApplicationHelper fails:

def tabular_form_for(name, object = nil, options = nil, &proc)
  concat("<table>", proc.binding)
           (options||{}).merge(:builder => TabularFormBuilder),
  concat("</table>", proc.binding)

But using this tag in my view, I get errors with my :errors, :name
fields of the form.
Any ideas how to make this custom tag work?