php - Class 'MongoClient' not found

环境：
PHP5.6.2
Apache2

安装php-mongo driver

[Jack:~ $] sudo pecl install mongo
pecl/mongo is already installed and is the same as the released version 1.6.14

[Jack:~ $] vi /etc/php.ini
extension=mongo.so

[Jack:~ $] apachectl restart

我已经安装php-mongo driver，php.ini也添加了扩展，但是还是报这个错，怎么破？
代码：

报错：

Fatal error: Class 'MongoClient' not found in /private/var/www/index.php on line 5