Getting a 422 error when trying to upload a file?

[shealan]

        $soundcloud = new \Soundcloud\Service(env('SOUNDCLOUD_ID'), env('SOUNDCLOUD_SECRET'));
        $soundcloud->setAccessToken('xxxxxxxxxxxxxxxxxxxxxx');

        $path = storage_path('app/test.mp3');

        $track = [
            'track[title]' => 'My amazing cool track',
            'track[tags]' => 'dubstep rofl',
            'track[asset_data]' => "@{$path}"
        ];

        try {
            return $soundcloud->post('tracks', $track);
        } catch (Services_Soundcloud_Invalid_Http_Response_Code_Exception $e) {
            exit($e->getMessage());
        }

Any ideas?