Delayed_Job NoMethodError when using Nginx - nginx

Question

I'm having trouble implementing the Delayed_Job_Active_Record gem in my Production Environment with Nginx. The user submits a 'Contact Us' form, the relevant controller action is called by Nginx and the following line of code fails:
#contact.delay.send_contact_form
Where the relevant method is:
def send_contact_form
ContactMailer.contact_us(self).deliver
end
Development Env: OK
On my local machine I have the pages served by Webrick. Everything runs fine, the delayed jobs go through the 'Delayed_Jobs' table and emails are sent.
Production Env - Rails Console: OK
On the server if I create #contact and call #contact.delay.send_contact_form manually, the delayed job goes through the delayed job table and email is sent.
Production Env - Webrick: OK
On the server if I start up a rails Webrick server I and enter the data for #contact via the web interface and then submit the job goes through the delayed job table and email is sent.
Production Env - Nginx: ERROR
The application is currently served by Nginx.
If I visit the interface via Nginx and enter the data for #contact and submit the page hangs.
The Production Log gives the following error on the controller action, (referencing the line above):
NoMethodError (undefined method `delay' for #< Contact:0x000000052962b0>)
I have also confirmed that the versions of Rails, Ruby and the Delayed_Job_Active_Record and Daemons gems are the same in both environments.
Any help would be greatly appreciated as i've been stuck on this one for a while. I want to find a solution that works with Nginx and which gives me the same functionality as 'Delayed Job'.
Thanks.

Answer 1

It turns out the problem was with Unicorn/Nginx not being restarted upon deployment of code updates, leaving them with incorrect configurations. The problem also occurred when adding Devise and other gems to the application.
The solution initially was to log into the VPS shell after a deployment, (via Capistrano) and run the following:
Restart Unicorn:
/etc/init.d/unicorn_esg stop
/etc/init.d/unicorn_esg start
Where *unicorn_esg* is the Unicorn reference to the application used in my deploy.rb configuration.
Restart Nginx:
sudo service nginx restart
The next step would be to incorporate this into the end of the deploy.rb script so it is automatically run at the end of each deployment.