Rails - Apr 2009 - TypeError Conversion on has_many relationship

I have a couple of objects in a Rails app ("Ticket", and
"Comment")

class Ticket < ActiveRecord::Base
  has_many    :attributes
  has_many    :comments
end

class Comment < ActiveRecord::Base
  belongs_to :ticket
  belongs_to :user
end
with the following schema:

create_table "comments", :force => true do |t|
  t.integer  "ticket_id"
  t.integer  "user_id"
  t.text     "content"
  t.datetime "created_at"
  t.datetime "updated_at"
end

create_table "tickets", :force => true do |t|
  t.integer  "site_id"
  t.integer  "status"
  t.integer  "user_id"
  t.datetime "created_at"
  t.datetime "updated_at"
end
However, for some reason - whenever I do a @lead.comments I get a
crash:

can''t convert String into Integer

Any ideas? This is driving me nuts!