How to use Amazon s3 in Codeigniter?

[eluser]tk123[/eluser]
I know there are a lot of CI libraries created to work with s3 but I would like to use the native PHP SDK released by amazon instead.

It works just fine when I use it outside CI, that is I am able to create buckets, upload files to them, etc. But when I put it inside CI and call it like so in my home controller:

Code:

require_once 'sdk-1.5.6.2/sdk.class.php';
$s3 = new AmazonS3();

I get the error:

Fatal error: Class 'AmazonS3' not found in /var/www/application/controllers/home.php on line 26

Same issue if I use the SDK as a CI Library. Does anyone know how to get this to work?