ArgumentError (interning empty string)

Hello,

I am trying to send an email out on registration for confirming and I am thrown this error. I am unable to understand as nothing is nil in the class which I am passing to the Mailer. Please do help me. The stack trace follows: ArgumentError (interning empty string):   app/controllers/accounts_controller.rb:103:in `register'   app/controllers/accounts_controller.rb:43:in `register'   /usr/lib/ruby/1.8/mongrel.rb:159:in `process_client'   /usr/lib/ruby/1.8/mongrel.rb:158:in `each'   /usr/lib/ruby/1.8/mongrel.rb:158:in `process_client'   /usr/lib/ruby/1.8/mongrel.rb:285:in `run'   /usr/lib/ruby/1.8/mongrel.rb:285:in `initialize'   /usr/lib/ruby/1.8/mongrel.rb:285:in `new'   /usr/lib/ruby/1.8/mongrel.rb:285:in `run'   /usr/lib/ruby/1.8/mongrel.rb:268:in `initialize'   /usr/lib/ruby/1.8/mongrel.rb:268:in `new'   /usr/lib/ruby/1.8/mongrel.rb:268:in `run'