CouchBase class not found in laravel5

I use couchbase nosql database by ytake/laravel-couchbase package in my laravel 5.1 project
After install that package and run php artisan serve i got error :

PHP Fatal error:  Class 'CouchbaseN1qlQuery' not found in /var/www/html/eee/vendor/ytake/laravel-couchbase/src/CouchbaseServiceProvider.php on line 71


 [Symfony\Component\Debug\Exception\FatalErrorException]  
 Class 'CouchbaseN1qlQuery' not found  

via Chebli Mohamed