hardcoded role

[ak4t0sh]

In

moodle-block_mystudents/view.php

Line 52 in c780831

list ($select, $from, $where, $params) = user_get_participants_sql($courseid, 0, 0, 5);

Role "5" is hardcoded. This role is usually 'student' but you can not be sure that's always true.
A cleaner way would be to fetch the id from database using the role shortname "student".
$DB->get_record('role', array('shortname' => 'student'));

Enhancement (non blocking for approval) :
IMO the best way would be to add a setting to select the students role(s) (some institutions can have several roles for students) :-)