Enroling course and role assignment through rest api

Hi All,

Im using moodle version-3.3 ,iam able to create users through rest API,but i m failing to assign roles and coures to that user presently im facing this error,plz check below.

{"exception":"moodle_exception","errorcode":"wsusercannotassign","message":"You don't have the permission to assign this role (5) to this user (323) in this course(26)."}

Thanks,

Eswar