Testing for Form Submission?

Hi-

I'm trying to create a file upload script using RoR but I am getting "You have a nil object when you didn't expect it!" and I think this is caused by the fact that the no form has been submitted. Is that right?

Here's the form:

<% form_for :dump, :url => { :controller => "mycontroller", :action=> "csv_reader" }, :html => { :multipart => true } do |f| -%> <table>         <tr>                 <label for="file">                 <td><b><i>Select a CSV File: </i></b></td>                 </label>                 <td><%= file_field_tag 'file' %></td>         </tr>         <tr>                 <td colspan='2'><%= submit_tag "Submit" %></td>         </tr> </table> <% end %>

Thanks!