Ошибка «неопределенный индекс: драйвер» при использовании neo4j в качестве базы данных для формы laravel

Мой сценарий:
Я написал форму с использованием фреймворка Laravel PHP. Я хочу, чтобы данные этой формы были сохранены в базе данных графиков (Neo4j DB). Вот мой app/config/database.php,

<?php

return array(

/*
|--------------------------------------------------------------------------
| PDO Fetch Style
|--------------------------------------------------------------------------
|
| By default, database results will be returned as instances of the PHP
| stdClass object; however, you may desire to retrieve records in an
| array format for simplicity. Here you can tweak the fetch style.
|
*/

'fetch' => PDO::FETCH_CLASS,

/*
|--------------------------------------------------------------------------
| Default Database Connection Name
|--------------------------------------------------------------------------
|
| Here you may specify which of the database connections below you wish
| to use as your default connection for all database work. Of course
| you may use many connections at once using the Database library.
|
*/

'default' => 'neo4j',

/*
|--------------------------------------------------------------------------
| Database Connections
|--------------------------------------------------------------------------
|
| Here are each of the database connections setup for your application.
| Of course, examples of configuring each database platform that is
| supported by Laravel is shown below to make development simple.
|
|
| All database work in Laravel is done through the PHP PDO facilities
| so make sure you have the driver for your particular database of
| choice installed on your machine before you begin development.
|
*/

'connections' => array(

'sqlite' => array(
'driver'   => 'sqlite',
'database' => __DIR__.'/../database/production.sqlite',
'prefix'   => '',
),

'mysql' => array(
'driver'    => 'mysql',
'host'      => 'localhost',
'database'  => 'appdb',
'username'  => 'root',
'password'  => 'password',
'charset'   => 'utf8',
'collation' => 'utf8_unicode_ci',
'prefix'    => '',
),

'pgsql' => array(
'driver'   => 'pgsql',
'host'     => 'localhost',
'database' => 'forge',
'username' => 'forge',
'password' => '',
'charset'  => 'utf8',
'prefix'   => '',
'schema'   => 'public',
),

'sqlsrv' => array(
'driver'   => 'sqlsrv',
'host'     => 'localhost',
'database' => 'database',
'username' => 'root',
'password' => '',
'prefix'   => '',
),
'neo4j' => array(
'host'     => 'localhost',
'port'     => 7474,
'username' => null,
'password' => null,
),

),

/*
|--------------------------------------------------------------------------
| Migration Repository Table
|--------------------------------------------------------------------------
|
| This table keeps track of all the migrations that have already run for
| your application. Using this information, we can determine which of
| the migrations on disk haven't actually been run in the database.
|
*/

'migrations' => 'migrations',

/*
|--------------------------------------------------------------------------
| Redis Databases
|--------------------------------------------------------------------------
|
| Redis is an open source, fast, and advanced key-value store that also
| provides a richer set of commands than a typical key-value systems
| such as APC or Memcached. Laravel makes it easy to dig right in.
|
*/

'redis' => array(

'cluster' => false,

'default' => array(
'host'     => '127.0.0.1',
'port'     => 6379,
'database' => 0,
),

),
);

Проблема столкнулась:
Когда я заполняю эту форму и нажимаю кнопку «Отправить», данные не попадают в базу данных neo4j. Он отображает ошибку:
ErrorException (E_UNKNOWN)
Неопределенный индекс: драйвер

Ожидаемый результат:
Данные формы должны быть сохранены в базе данных neo4j при нажатии на кнопку отправки.