Laravel 4 Mail не работает с помощью транзакционного почтового провайдера

В данный момент я работаю с Laravel 4, хочу подключиться к транзакционному серверу, Sparkpost также делает все, что мне нужно, но у меня возникают проблемы с его реализацией, всякий раз, когда я использую Mail :: send (), я получаю следующее ошибка,

Тип swift.transport не связан.

Я не могу найти ссылки на эту ошибку где-либо в Интернете, есть ли у кого-нибудь опыт внедрения Sparkpost и Laravel 4, это мой почтовый конфигурационный файл,

<?php

return array(

/*
|--------------------------------------------------------------------------
| Mail Driver
|--------------------------------------------------------------------------
|
| Laravel supports both SMTP and PHP's "mail" function as drivers for the
| sending of e-mail. You may specify which one you're using throughout
| your application here. By default, Laravel is setup for SMTP mail.
|
| Supported: "smtp", "mail", "sendmail", "mailgun", "mandrill", "log"|
*/

'driver' => 'sparkpost',

/*
|--------------------------------------------------------------------------
| SMTP Host Address
|--------------------------------------------------------------------------
|
| Here you may provide the host address of the SMTP server used by your
| applications. A default option is provided that is compatible with
| the Mailgun mail service which will provide reliable deliveries.
|
*/

'host' => 'smtp.sparkpostmail.com',

/*
|--------------------------------------------------------------------------
| SMTP Host Port
|--------------------------------------------------------------------------
|
| This is the SMTP port used by your application to deliver e-mails to
| users of the application. Like the host we have set this value to
| stay compatible with the Mailgun e-mail application by default.
|
*/

'port' => 587,

/*
|--------------------------------------------------------------------------
| Global "From" Address
|--------------------------------------------------------------------------
|
| You may wish for all e-mails sent by your application to be sent from
| the same address. Here, you may specify a name and address that is
| used globally for all e-mails that are sent by your application.
|
*/

'from' => array('address' => '[email protected]', 'name' => 'xxxxx noreply'),

/*
|--------------------------------------------------------------------------
| E-Mail Encryption Protocol
|--------------------------------------------------------------------------
|
| Here you may specify the encryption protocol that should be used when
| the application send e-mail messages. A sensible default using the
| transport layer security protocol should provide great security.
|
*/

'encryption' => 'STARTTLS',

/*
|--------------------------------------------------------------------------
| SMTP Server Username
|--------------------------------------------------------------------------
|
| If your SMTP server requires a username for authentication, you should
| set it here. This will get used to authenticate with your server on
| connection. You may also set the "password" value below this one.
|
*/

'username' => "SMTP_Injection",

/*
|--------------------------------------------------------------------------
| SMTP Server Password
|--------------------------------------------------------------------------
|
| Here you may set the password required by your SMTP server to send out
| messages from your application. This will be given to the server on
| connection so that the application will be able to send messages.
|
*/

'password' => $_ENV['sparkpost_secret'],

/*
|--------------------------------------------------------------------------
| Sendmail System Path
|--------------------------------------------------------------------------
|
| When using the "sendmail" driver to send e-mails, we will need to know
| the path to where Sendmail lives on this server. A default path has
| been provided here, which will work well on most of your systems.
|
*/

'sendmail' => '/usr/sbin/sendmail -bs',

/*
|--------------------------------------------------------------------------
| Mail "Pretend"|--------------------------------------------------------------------------
|
| When this option is enabled, e-mail will not actually be sent over the
| web and will instead be written to your application's logs files so
| you may inspect the message. This is great for local development.
|
*/

'pretend' => false,

);

Кто-нибудь какие-либо идеи, где я ошибся, я использую Sparkpost через этот пакет,

https://packagist.org/packages/clarification/sparkpost-laravel-driver

Я добавил службы в мой файл service.php, а также добавил пакет в массив моих провайдеров.