7 – Drupal how to use the function of libraries.

I have the library module to add some libraries to my drupal site.
Currently I need to use Mailjet, I found some modules with some functions to talk to api, but I have tried it for several hours and I can not make this work (the functions do not work if I do not modify them).

So I want to use the official php library for MailJet, download it and place it in the sites / all / library folder.

In my module I try to call this library but it does not work:

Here is an attempt with the detection libraries:

    $ name = & # 39; mailjet & # 39 ;;
if (($ library = library_detect ($ name)) &&! empty ($ library['installed']))
{
// The library is installed. Amazing!
dsm ("installed");
}
else {
// Something went wrong. : déçu:
// This contains a short status code of what went wrong, such as & # 39; not found & # 39;.
$ error = $ library['error'];
// This contains a detailed (localized) error message.
$ error_message = $ library['error message'];
}

Always pass the other, and here with library_load:

if (($ library = library_load (& # 39; mailjet & # 39;)) &&! empty ($ library['loaded'])) {
// Do something with the library here.
dsm ("loaded");
} else {
dsm (& # 39; not loaded & # 39;);
}

The same, always in the other.

What am I doing wrong ?