Yii2 migration transaction methods, safeup() and safedown() not working

I am using the safeUp and safeDown methods for Database transactions in yii but it seems not to be working. Here is my code below:

    public function safeUp()
{
    $this->createTable(self::TABLE_EMPLOYMENT_HISTORY, [
        'id' => $this->integer() . ' UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY',
        'user_id' => $this->integer()->unsigned()->notNull(),
        'start_date' => $this->dateTime()->notNull(),
        'end_date' => $this->dateTime(),
        'role' => $this->string(150)->notNull(),
        'position' => $this->string(50)->notNull(),
        'achievements' => $this->text(),
        'created_at' => $this->dateTime()->notNull(),
        'updated_at' => $this->dateTime()->notNull(),
        'status' => $this->string(50)->notNull()
    ]);
    $this->addForeignKey('fk_' . self::TABLE_EMPLOYMENT_HISTORY . '_' . self::TABLE_USERS . '_id', self::TABLE_EMPLOYMENT_HISTORY, 'user_id', self::TABLE_USERS, 'id');
    $this->addForeignKey('fk_' . self::TABLE_EMPLOYMENT_HISTORY . '_' . self::TABLE_STATUSES . '_key', self::TABLE_MISTAKE, 'status', self::TABLE_STATUSES, 'key');
}

public function safeDown()
{
    $this->dropForeignKey('fk_' . self::TABLE_EMPLOYMENT_HISTORY . '_' . self::TABLE_STATUSES . '_key', self::TABLE_EMPLOYMENT_HISTORY);
    $this->dropForeignKey('fk_' . self::TABLE_EMPLOYMENT_HISTORY . '_' . self::TABLE_USERS . '_id', self::TABLE_EMPLOYMENT_HISTORY);
    $this->dropTable(self::TABLE_EMPLOYMENT_HISTORY);

}

When I ran that, It said of course that the table TABLE_MISTAKE does not exist when trying to create the foreign key. I was expecting a rollback but that did not happen, instead, it went ahead to create the table 'EMPLOYMENT_HISTORY'.

Why is it creating the table despite using the safeup method?

Your help would be appreciated.