Twitch API - checkChannelSubsription returns null

[Aresak]

$interface = new twitch;
var_dump($interface->checkChannelSubscription($a->username, aresak_config::$streamerName, $a->token, $a->code));
var_dump($a->username);
var_dump($a->token);
var_dump($a->code);
var_dump(aresak_config::$streamerName);

As you can see this is valid code. Made with var_dumps so you will see the result.
This is the result:

NULL
string(6) “aresak”
string(30) “2gmrcensoredyxy9bllp4p0qjuxitc”
string(30) “ib1slcensoredsl0t654kaspcbvsa0”
string(5) “lirik”

Do you have any ideas?
Thanks you for any suggestions and fixes.

Using Twitch_Interface Twitch_Interface.

[Fugiman]

According to Twitch Interface it seems it’ll return null on error?