Just downloaded Survey2/"collection" mod from github. $module->version = 2012101103
on Moodle 2.4 (master) version Moodle 2.4dev (Build: 20121101)
Windows 7. Moodle database: MySQL
localhost
I can create questions, but Impossible to take a survey, always getting error message:

Debug info: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ra
JOIN mdl_user u ON u.id = ra.userid' at line 5
SELECT DISTINCT ra.userid, u.firstname, u.lastname, u.email
FROM (SELECT *
FROM mdl_role_assignments
WHERE contextid = 28
AND roleid IN (Array) ra
JOIN mdl_user u ON u.id = ra.userid
[array (
)]
Error code: dmlreadexception
Stack trace:
line 424 of \lib\dml\moodle_database.php: dml_read_exception thrown
line 960 of \lib\dml\mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1972 of \mod\collection\locallib.php: call to mysqli_native_moodle_database->get_recordset_sql()
line 146 of \mod\collection\beforepage.php: call to collection_notifyroles()
line 58 of \mod\collection\view.php: call to include_once()