Couchbase Server 4.6 - PHP SDK : Fatal error: Class ‘Couchbase’ not found

Couchbase Server 4.6 - PHP SDK : Fatal error: Class ‘Couchbase’ not found

I have installed PHP SDK with couchbase sever 4.6 on Ubuntu 16.04 following this installation Guide here:
https://developer.couchbase.com/documentation/server/4.6/sdk/php/start-using-sdk.html

But I’m still getting error like Fatal error: Uncaught Error: Class ‘CouchbaseCluster’ not found in /home/admin/web/deamonv2.loc/public_html/hello.php:18 Stack trace: #0 {main} thrown

I’m running PHP Version 7.0 on Ubuntu 16.04

tried everything not working for me. any Help would be appriciated.strong text

Sorry Duplicate Post to this one