diff --git a/booking.variety_admin.inc b/booking.variety_admin.inc
index 4341873..52ffc5a 100644
--- a/booking.variety_admin.inc
+++ b/booking.variety_admin.inc
@@ -764,20 +764,33 @@ function booking_variety_regn_edit_form_submit($form, &$form_state) {
 
     foreach ($previous_variety_ids as $previous_tid => $previous_sid) {
       if ($booking_variety_ids[$previous_tid] != $previous_sid) {
+        // reduce regn count for old session
+        db_update('booking_variety_sessions')
+          ->expression('booking_variety_regncount', 'booking_variety_regncount - :count', array(':count' => 1))
+          ->condition('vid', $previous_sid)
+          ->execute();  
+
+        // increase regn count for new session
+        db_update('booking_variety_sessions')
+          ->expression('booking_variety_regncount', 'booking_variety_regncount - :count', array(':count' => 1))
+          ->condition('vid', $booking_variety_ids[$previous_tid])
+          ->execute();         
+
         watchdog('booking_debug', 'Person @nid in timeslot @tid previously registered for session id @vid but new value is @new', array(
           '@nid' => $values['nid'], '@tid' => $previous_tid, '@vid' => $previous_sid, '@new' => $booking_variety_ids[$previous_tid]
         ));        
       }
     }
-    /*
+
+    // update the session registration information for this person
 		$result = db_update('booking_variety_regn')
 			->fields(array(
-        'booking_variety_ids' => drupal_json_encode(),
+        'booking_variety_ids' => drupal_json_encode($booking_variety_ids),
 			))
 			->condition('booking_person_nid', $values['nid'])
 			->execute();
-      watchdog('booking', "Updated variety session registration for person ID !nid", array('!nid' => $values['nid']));
-    */
+    watchdog('booking', "Updated variety session registration for person ID !nid", array('!nid' => $values['nid']));
+
 		$form_state['redirect'] = $redirect_path;
 	}
 }