Why don't submodules work?

Question

git

Hello!
I have in the project folder .gitmodules the following content:

[submodule "vendor/symfony"]
  path = vendor/symfony
  url = git://github.com/symfony/symfony.git
[submodule "src/Bundle/LichessBundle/Resources/public/vendor/pgn4web"]
  path = src/Bundle/LichessBundle/Resources/public/vendor/pgn4web
  url = git://github.com/ornicar/pgn4web.git
[submodule "src/Bundle/ForumBundle"]
  path = src/Bundle/ForumBundle
  url = git://github.com/Herzult/ForumBundle.git
[submodule "vendor/mongodb-odm"]
  path = vendor/mongodb-odm
  url = git://github.com/doctrine/mongodb-odm
[submodule "src/Knplabs/TimeBundle"]
  path = src/Knplabs/TimeBundle
  url = git://github.com/knplabs/TimeBundle.git
[submodule "vendor/zend"]
  path = vendor/zend
  url = git://github.com/zendframework/zf2.git
[submodule "vendor/ZendPaginatorAdapter"]
  path = vendor/ZendPaginatorAdapter
  url = git://github.com/ornicar/ZendPaginatorAdapter.git
[submodule "src/Bundle/ApcBundle"]
  path = src/Bundle/ApcBundle
  url = git://github.com/ornicar/ApcBundle.git
[submodule "vendor/twig"]
  path = vendor/twig
  url = git://github.com/fabpot/Twig.git
[submodule "vendor/php-git-repo"]
  path = vendor/php-git-repo
  url = git://github.com/ornicar/php-git-repo.git
[submodule "src/Bundle/LichessBundle"]
  path = src/Bundle/LichessBundle
  url = git://github.com/ornicar/LichessBundle.git
[submodule "vendor/Doctrine2-Sluggable-Functional-Behavior"]
  path = vendor/Doctrine2-Sluggable-Functional-Behavior
  url = git://github.com/ornicar/Doctrine2-Sluggable-Functional-Behavior.git
[submodule "src/FOS/UserBundle"]
  path = src/FOS/UserBundle
  url = git://github.com/FriendsOfSymfony/UserBundle.git
[submodule "src/Bundle/Ornicar/MessageBundle"]
  path = src/Bundle/Ornicar/MessageBundle
  url = git://github.com/ornicar/MessageBundle
[submodule "vendor/doctrine-data-fixtures"]
  path = vendor/doctrine-data-fixtures
  url = git://github.com/doctrine/data-fixtures

But when executed
git submodules init, git submodules updatenothing happens, the library files are not loaded. What's wrong?

Answer 1

Just add submodules using command
This does more than just adding text to .gitmodules. And commit these changes, then everything will work as it should.