Php 找不到版本号为1的迁移

我试图在youtube上关注codeigniter tutorail关于在codeigniter中创建迁移的内容。然而，我犯了一个错误

找不到版本号为1的迁移

我已经设置了$config['migration_version']=1；在Application/Config/migration.php和我的迁移文件中创建用户表

Application/migrations/001\u Create\u User.php

   <?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Migration_Create_Users extends CI_Migration {

/*
up function is for creating and alert table
*/
        public function up()
        {
                $this->dbforge->add_field(array(
                        'id' => array(
                                'type' => 'INT',
                                'constraint' => 11,
                                'unsigned' => TRUE,
                                'auto_increment' => TRUE
                        ),
                        'email' => array(
                                'type' => 'VARCHAR',
                                'constraint' => '128',
                        ),
                        'password' => array(
                                'type' => 'VARCHAR',
                                'constraint' => '100',
                        ),
                ));
                $this->dbforge->add_key('id',TRUE);
                $this->dbforge->create_table('users');
        }

/*
down function for rollback table
*/
        public function down()
        {
                $this->dbforge->drop_table('users');
        }
}
?>

当我检查数据库时，我看到迁移表的版本总是0

---

请帮助我，谢谢config/migration.php中的

 /*
    |--------------------------------------------------------------------------
    | Migration Type
    |--------------------------------------------------------------------------
    |
    | Migration file names may be based on a sequential identifier or on
    | a timestamp. Options are:
    |
    |   'sequential' = Default migration naming (001_add_blog.php)
    |   'timestamp'  = Timestamp migration naming (20121031104401_add_blog.php)
    |                  Use timestamp format YYYYMMDDHHIISS.
    |
    | If this configuration value is missing the Migration library defaults
    | to 'sequential' for backward compatibility.
    |
    */
    $config['migration_type'] = 'sequential';