[SOLVED]Class as Library

HI , i try to use this class :

https://github.com/bluerhinos/phpMQTT

as library .

I change class name as PhpMQTT

and load the library :

Code:

    $params = array('address' => $server, 'port' => $port ,'clientid' => $client_id );
    $this->load->library('phpMQTT',$params);

but when i call a method of library i have :


Message: Undefined property: Ajax_call_device::$phpMQTT on line 283

this is the 283 line :

if ($this->phpMQTT->connect(true, NULL, $username, $password)) 

How can i solve ?