"NoMethodError: undefined method `type' for "character varying":String" after "rake db:migrate"

I tried to add checkins to microposts but I've got an error after rake db:migrate.. What does it mean?

Error

  $ rake db:migrate --trace
    ** Invoke db:migrate (first_time)
    ** Invoke environment (first_time)
    ** Execute environment
    ** Invoke db:load_config (first_time)
    ** Execute db:load_config
    ** Execute db:migrate
    rake aborted!
    NoMethodError: undefined method `type' for "character varying":String

add_checkin_to_microposts

 class AddCheckinToMicroposts < ActiveRecord::Migration
   def change
      add_column :microposts, :location, :point, :geographic => true
   end
 end

database.yml

 development:
  adapter: postgresql
  schema_search_path: public, postgis
  encoding: unicode
  database: blog_development
  host: localhost
  pool: 5
  username: ******** 
  password: