Create Plan With Rest API Fails

[agilelogix]

I'm trying to Implement REST API  Create Plan using the PHP SDK but I'm getting this error.

PayPal-PHP-SDK/sample/billing/CreatePlan.php

{
    "name": "REQUIRED_SCOPE_MISSING",
    "message": "Access token does not have required scope",
    "information_link": "https://developer.paypal.com/webapps/developer/docs/api/#REQUIRED_SCOPE_MISSING",
    "debug_id": "d87a25f6236eb"
}

 Both my sandbox and the live app has features enabled, but still, I'm receiving such error. Can anyone point out the problem?

Thanks