SQL error in scheduled job

The scheduled job named "Scheduled reminders sender" is failing sue to an invalid SQL statement.

The SQL statement is "INSERT INTO civicrm_action_log (contact_id, entity_id, entity_table, action_schedule_id)
SELECT r.assignee_contact_id as contact_id, e.id as entity_id, 'civicrm_activity' as entity_table, 2 as action_schedule_id
FROM civicrm_activity e
INNER JOIN civicrm_contact c ON c.id = r.assignee_contact_id
LEFT JOIN civicrm_action_log reminder ON reminder.contact_id = r.assignee_contact_id AND
reminder.entity_id = e.id AND
reminder.entity_table = 'civicrm_activity' AND
reminder.action_schedule_id = 2
WHERE e.activity_type_id IN (14) AND e.status_id IN (1) AND e.is_current_revision = 1 AND e.is_deleted = 0 AND r.assignee_contact_id IN (11833) AND c.is_deleted = 0 AND reminder.id IS NULL AND DATEDIFF(DATE('20120928181427'),'2012-09-21') = 0"

This is not happening in the public demo. I would like to help trouble-shoot this futher, but am unable to get a stack trace. I have "enable debugging" and "Display Backtrace" enabled in the GUI. I also have the entries
define( 'CIVICRM_DEBUG_LOG_QUERY', 1 );
define( 'CIVICRM_DEBUG_LOG_QUERY', 'backtrace' );

In my civicrm.settings.php file.

The output in the job log from the scheduled job is:
Parameters parsed (and passed to API method):
a:2:

{s:7:"version";i:3;s:5:"debug";s:1:"1";}

Full message:
Finished execution of Scheduled reminders sender with result: Failure, Error message: DB Error: no such field