diff --git a/booking.variety_form.inc b/booking.variety_form.inc
index c1e7d2d..9d8034c 100644
--- a/booking.variety_form.inc
+++ b/booking.variety_form.inc
@@ -131,7 +131,8 @@ function booking_variety_session_callback($form, &$form_state) {
     $options = _booking_get_variety_timeslot_options($timeslot->tid);
     watchdog('booking_debug', 'Timeslot @tid form state value: <pre>@info</pre>', 
       array('@tid' => $timeslot->tid, '@info' => print_r($form_state['values'], true)));
-      watchdog('booking_debug', $options[$form_state['values'][$fieldname]]);
+      watchdog('booking_debug', 'Setting default value to @value', array('@value' => 
+        isset($form_state['values'][$fieldname]) ? $options[$form_state['values'][$fieldname]] : 0));
 
     //re-create the form element for this timeslot
     $form['variety-sessions'][$fieldname] = array(