我在安装Propel时遇到问题，sql：build不起作用

I am following the official Propel tutorial: Propel chapter 2: build time

But when I execute the vendor/bin/propel sql:build script, nothing happens!

I created a composer.json file and then installed composer, just as explained. The files are succesfully downloaded.

I go to my project: /media/sf_sandbox/test/temp/propel/bookstore

I used the example for the schema.xml file:

    <?xml version="1.0" encoding="UTF-8"?>
<database name="bookstore" defaultIdMethod="native">
  <table name="book" phpName="Book">
    <column name="id" type="integer" required="true" primaryKey="true" autoIncrement="true"/>
    <column name="title" type="varchar" size="255" required="true" />
    <column name="isbn" type="varchar" size="24" required="true" phpName="ISBN"/>
    <column name="publisher_id" type="integer" required="true"/>
    <column name="author_id" type="integer" required="true"/>
    <foreign-key foreignTable="publisher" phpName="Publisher" refPhpName="Book">
      <reference local="publisher_id" foreign="id"/>
    </foreign-key>
    <foreign-key foreignTable="author">
      <reference local="author_id" foreign="id"/>
    </foreign-key>
  </table>
  <table name="author" phpName="Author">
    <column name="id" type="integer" required="true" primaryKey="true" autoIncrement="true"/>
    <column name="first_name" type="varchar" size="128" required="true"/>
    <column name="last_name" type="varchar" size="128" required="true"/>
  </table>
  <table name="publisher" phpName="Publisher">
   <column name="id" type="integer" required="true" primaryKey="true" autoIncrement="true" />
   <column name="name" type="varchar" size="128" required="true" />
  </table>
</database>

I used the propel.php example with my username and password, I kept the rest unchanged:

<?php

return [
    'propel' => [
        'database' => [
            'connections' => [
                'bookstore' => [
                    'adapter'    => 'mysql',
                    'classname'  => 'Propel\Runtime\Connection\ConnectionWrapper',
                    'dsn'        => 'mysql:host=localhost;dbname=my_db_name',
                    'user'       => 'myusername',
                    'password'   => 'mypassword',
                    'attributes' => []
                ]
            ]
        ],
        'runtime' => [
            'defaultConnection' => 'bookstore',
            'connections' => ['bookstore']
        ],
        'generator' => [
            'defaultConnection' => 'bookstore',
            'connections' => ['bookstore']
        ]
    ]
];

But when I execute this script: vendor/bin/propel sql:build

But nothing happens, no new database, no error, it just repeats this line:

/media/sf_sandbox/test/temp/propel/bookstore
/media/sf_sandbox/test/temp/propel/bookstore

The path to my project, I just can't get my head around this...