title: Can't revoke an user role
body: <p>I have an role which which exists in sys.dba_roles, and it is assigned to an user. When I want to revoke the role from the user who has it  however I'm getting the error:</p>
  
  <blockquote>
    <p>ORA-01924: role 'MY_ROLE' not granted or does not exist.</p>
  </blockquote>
  
  <p>When I check the roles for the user with problems with:</p>
  
  <p><code>SELECT * FROM DBA_ROLE_PRIVS where GRANTEE='MY USER'</code> the role it's still there.</p>
  
  <p>How can I remove the role, or see which schema owns it ?</p>
  
  <p>Sincerely,</p>