The error means what it says, that @publishers is nil. Presumably
something has gone wrong in your create method. Have a look in the
log (log/development.log) to see if you get any clues. Otherwise you
could debug into create and see what is happening. Have a look at the
rails guide on debugging (http://guides.rubyonrails.org/) and also the
Getting Started guide if you have not already worked through that.