herokuでデプロイまではできたのですが、heroku run rake db:migrateをすると
エラーがでてしまいます。
昨夜から色々やってみたのですが、どうにもわかりません

6行目はActiveAdmin.routes(self)

devise_for :admin_users, ActiveAdmin::Devise.config
ActiveAdmin.routes(self)

git push heroku master

remote: -----> Discovering process types
remote:        Procfile declares types -> (none)
remote:        Default types for Ruby  -> console, rake, web, worker
remote: 
remote: -----> Compressing... done, 45.8MB
remote: -----> Launching... done, v6
remote:        https://afternoon-caverns-3384.herokuapp.com/ deployed to Heroku
remote: 
remote: Verifying deploy.... done.
To https://git.heroku.com/afternoon-caverns-1543.git
 * [new branch]      master -> master

heroku run rake db:migrate

hogehoge-no-MacBook-Air:jaco-ver4.0.0 hoge$ heroku run rake db:migrate
Running `rake db:migrate` attached to terminal... up, run.6083
PG::Error: ERROR:  relation "items" does not exist
LINE 5:                WHERE a.attrelid = '"items"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"items"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

rake aborted!
ActiveAdmin::DatabaseHitDuringLoad: Your file, app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.6/lib/active_record/connection_adapters/postgresql_adapter.rb (line 822), caused a database error while Active Admin was loading. This is most common when your database is missing or doesn't have the latest migrations applied. To prevent this error, move the code to a place where it will only be run when a page is rendered. One solution can be, to wrap the query in a Proc.Original error message: PG::Error: ERROR:  relation "items" does not exist
LINE 5:                WHERE a.attrelid = '"items"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"items"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/error.rb:43:in `rescue in capture'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/error.rb:41:in `capture'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/application.rb:203:in `load'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/application.rb:195:in `block in load!'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/application.rb:195:in `each'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/application.rb:195:in `load!'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin/application.rb:217:in `routes'
/app/vendor/bundle/ruby/2.0.0/bundler/gems/active_admin-7e72b7881eb6/lib/active_admin.rb:78:in `routes'
/app/config/routes.rb:6:in `block in <top (required)>'
/app/vendor/bundle/ruby/2.0.0/gems/actionpack-4.1.6/lib/action_dispatch/routing/route_set.rb:337:in `instance_exec'
/app/vendor/bundle/ruby/2.0.0/gems/actionpack-4.1.6/lib/action_dispatch/routing/route_set.rb:337:in `eval_block'
/app/vendor/bundle/ruby/2.0.0/gems/actionpack-4.1.6/lib/action_dispatch/routing/route_set.rb:315:in `draw'
/app/config/routes.rb:1:in `<top (required)>'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:241:in `load'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:241:in `block in load'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:232:in `load_dependency'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:241:in `load'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:40:in `each'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:40:in `load_paths'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:16:in `reload!'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:26:in `block in updater'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/file_update_checker.rb:75:in `call'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/file_update_checker.rb:75:in `execute'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:27:in `updater'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application/finisher.rb:71:in `block in <module:Finisher>'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/initializable.rb:30:in `instance_exec'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/initializable.rb:30:in `run'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/initializable.rb:55:in `block in run_initializers'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/initializable.rb:54:in `run_initializers'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application.rb:300:in `initialize!'
/app/config/environment.rb:5:in `<top (required)>'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:247:in `require'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:247:in `block in require'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:232:in `load_dependency'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.6/lib/active_support/dependencies.rb:247:in `require'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application.rb:276:in `require_environment!'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.1.6/lib/rails/application.rb:389:in `block in run_tasks_blocks'
Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)