error/moodle/nopermissions
From MoodleDocs
This is a general error that indicates the user are logged in as does not have permissions to do what you were attempting.
This is part of the new Roles framework in Moodle 1.7. If you believe that your roles for that user DO allow that action you were attempting, then you may have found a bug. Congratulations! Please help us by filing the bug at http://moodle.org/bugs.