ActiveRecord::StatementInvalid: Mysql2::Error: Table doesn't exist

ActiveRecord::StatementInvalid: Mysql2::Error: Table doesn't exist

I'm trying to create simple internal messaging service for that i have
used devise for authentication so i have users table. I have created a
messages table for messages and a join table called messages_users. I want
to use has_many through association so my associations are like this:-
user.rb :-
has_many :sent_messages, class_name: "Message", foreign_key: "user_id"
has_many :message_users
has_many :received_messages, through: :message_users, source: :message
message.rb:-
belongs_to :User
has_many :message_users
has_many :receivers, through: :message_users, source: :user
message_user.rb :-
class MessageUser < ActiveRecord::Base
belongs_to :User
belongs_to :message
end
and schema.rb :-
ActiveRecord::Schema.define(version: 20130912100741) do
create_table "messages", force: true do |t|
t.text "subject"
t.text "body", limit: 2147483647
t.integer "user_id"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "messages_users", id: false, force: true do |t|
t.integer "user_id", null: false
t.integer "message_id", null: false
end
add_index "messages_users", ["message_id"], name:
"index_messages_users_on_message_id", using: :btree
add_index "messages_users", ["user_id"], name:
"index_messages_users_on_user_id", using: :btree
create_table "users", force: true do |t|
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string "current_sign_in_ip"
t.string "last_sign_in_ip"
t.string "confirmation_token"
t.datetime "confirmed_at"
t.datetime "confirmation_sent_at"
t.string "unconfirmed_email"
t.integer "failed_attempts", default: 0
t.string "unlock_token"
t.datetime "locked_at"
t.string "authentication_token"
t.datetime "created_at"
t.datetime "updated_at"
t.string "provider"
t.string "uid"
t.string "name"
end
add_index "users", ["authentication_token"], name:
"index_users_on_authentication_token", unique: true, using: :btree
add_index "users", ["confirmation_token"], name:
"index_users_on_confirmation_token", unique: true, using: :btree
add_index "users", ["email"], name: "index_users_on_email", unique: true,
using: :btree
add_index "users", ["reset_password_token"], name:
"index_users_on_reset_password_token", unique: true, using: :btree
add_index "users", ["unlock_token"], name: "index_users_on_unlock_token",
unique: true, using: :btree
end
It works fine when i use user_object.sent_messages but when i use
user_object.received_messages it gives me Mysql2::Error: Table
'to_do.message_users' doesn't exist: SHOW FULL FIELDS FROM message_users
ActiveRecord::StatementInvalid: Mysql2::Error: Table 'to_do.message_users'
doesn't exist error. I want to use has_many through only and not habtm.
There were a couple of questions here on stackoverflow but none of them
solved my issue so any suggestions?