Error when loading extension

Im trying hello-couchbase.php and got error:

Fatal error: Class ‘CouchbaseCluster’ not found in /var/www/couchbase/hello-couchbase.php on line 5

Im loaded extension into php.ini and check:
$php -m | grep couchbase
Result: couchbase // It’s mean couchbase extension is loaded.

My phpinfo can not load couchbase info into.
Im using Ubuntu 14.04 64bit.
What’s my proplem?

Can you verify the version of the PECL extension? The pre-2.0 versions didn’t have a CouchbaseCluster class.