Mailer method missing

Rails dies when I try to call a method from my Mailer. But I have
defined my method. What could I have missed? Here is the irb session:

>> p = Person.find(1)
=> Person data...

>> SiteMailer.request_admin_approval(p)
NoMethodError: undefined method `request_admin_approval' for
SiteMailer:Class

>> SiteMailer.method_defined? :request_admin_approval
=> true

The method code:

class SiteMailer < ActionMailer::Base

  def request_admin_approval(person)
    @subject = 'Watercooler - New User Notification'
    @body["person"] = person
    @recipients = "me"
    @from = 'server@buwatercooler.org'
    @sent_on = Time.now
    @headers = {}
  end