MissingCredentialsError　で投稿ができない

記事投稿アプリを作成中です。投稿ページの入力フォームから画像を投稿しようとすると、

Aws::Sigv4::Errors::MissingCredentialsError in MicropostsController#create

Cannot load `Rails.config.active_storage.service`: missing credentials, 
provide credentials with one of the following 
」options: - :access_key_id and :secret_access_key - :credentials - :credentials_provider

と出てしまい、失敗します。
active_strageはインストールずみで、
アクセスキーとシークレットアクセスキーは渡せているはずなのですが、AWSのS3　と紐付けできていないようです。

config/environments/development.rb

  # 中略
  # Store uploaded files on the local file system (see config/storage.yml for options)
  config.active_storage.service = :amazon

config/storage.yml

# Use rails credentials:edit to set the AWS secrets (as aws:access_key_id|secret_access_key)
amazon:
  service: S3
  access_key_id: <%= Rails.application.credentials.dig(:aws, :access_key_id) %>
  secret_access_key: <%= Rails.application.credentials.dig(:aws, :secret_access_key) %>
  region: ap-northeast-1
  bucket:XXX-bucket

(キーはRails Credentialsで渡しています)

エラーが出るときのログ

Started POST "/microposts" for ::1 at 2019-12-18 13:16:51 +0900
Processing by MicropostsController#create as HTML
  Parameters: {"authenticity_token"=>"rVpTQA9KYUjCWcq//d4EvRSSmZkWcQdY9G+12lZIoDMZoIU05qWSZtU0zm+xv90nzCJkJFYlwkj3gtU4B0lIaw==",
 "micropost"=>{"memo"=>"", "picture"=>#<ActionDispatch::Http::UploadedFile:0x00007fcb10660ae8 
@tempfile=#<Tempfile:/var/folders/jn/s2wp92fd1bnfcjkt6hk6zjr40000gn/T/RackMultipart20191218-99657-14neqtw.png>, 
@original_filename="camera.png", @content_type="image/png",
 @headers="Content-Disposition: form-data; name=\"micropost[picture]\"; filename=\"camera.png\"\r\nContent-Type: image/png\r\n">}, "commit"=>"記録する"}
  User Load (0.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  ↳ app/helpers/sessions_helper.rb:16:in `current_user'
Creating scope :unattached. Overwriting existing method ActiveStorage::Blob.unattached.
Completed 500 Internal Server Error in 1012ms (ActiveRecord: 0.2ms | Allocations: 6999)


  
Aws::Sigv4::Errors::MissingCredentialsError (Cannot load `Rails.config.active_storage.service`:
missing credentials, provide credentials with one of the following options:
  - :access_key_id and :secret_access_key
  - :credentials
  - :credentials_provider):
  
app/models/micropost.rb:16:in `only_user_id'
app/controllers/microposts_controller.rb:11:in `create'

バケットと　テーブルは存在しているのになぜ紐付けができていないのでしょうか。。。

active_storageのミグレーションファイル

# This migration comes from active_storage (originally 20170806125915)
class CreateActiveStorageTables < ActiveRecord::Migration[5.2]
  def change
    create_table :active_storage_blobs do |t|
      t.string   :key,        null: false
      t.string   :filename,   null: false
      t.string   :content_type
      t.text     :metadata
      t.bigint   :byte_size,  null: false
      t.string   :checksum,   null: false
      t.datetime :created_at, null: false

      t.index [ :key ], unique: true
    end

    create_table :active_storage_attachments do |t|
      t.string     :name,     null: false
      t.references :record,   null: false, polymorphic: true, index: false
      t.references :blob,     null: false

      t.datetime :created_at, null: false

      t.index [ :record_type, :record_id, :name, :blob_id ], name: "index_active_storage_attachments_uniqueness", unique: true
      t.foreign_key :active_storage_blobs, column: :blob_id
    end
  end
end

もしくはdbの形式がおかしいのでしょうか。。。

どなたか原因が分かる方はいらっしゃいませんか？