API test for Moodle (v2.6) with Postman

Objective is to use the Moodle web services to fetch information via Postman. In this case - Webservice function : core_enrol_get_enrolled_users - Already created a user that had the rights to access the content - wsToken used as a parameter When sending the GET command in Postman, getting the below error <?xml version="1.0" encoding="UTF-8" ?> <EXCEPTION class="webservice_access_exception"> <ERRORCODE>accessexception</ERRORCODE> <MESSAGE>Access control exception</MESSAGE> </EXCEPTION> What are the possible missing configuration for the above error ?