Validator not quite working

Hi guys, I'm trying to get the form validator to work - and it almost does. What happens, I believe, is that it throws the error properly, but it never makes it back to the page to post the error. Instead, it kind of blows up.

I used the same basic code the scaffold uses, so I'm not sure why it's not working. If you guys wouldn't mind... controller = Signups, model = Customer

Cheers. And thanks in advance!

The error message: http://farm4.static.flickr.com/3259/3120802163_cefc0d789f_o.jpg

SignupsController http://www.pastie.org/343627

Index View http://www.pastie.org/343631

Customer model

class Customer < ActiveRecord::Base   validates_presence_of :first_name, :last_name, :email end