Index: trunk/core/kernel/db/db_event_handler.php
===================================================================
diff -u -r4325 -r4358
--- trunk/core/kernel/db/db_event_handler.php	(.../db_event_handler.php)	(revision 4325)
+++ trunk/core/kernel/db/db_event_handler.php	(.../db_event_handler.php)	(revision 4358)
@@ -1603,15 +1603,20 @@
 		function OnCreateCustomFields(&$event)
 		{
 			$main_prefix = $this->Application->getUnitOption($event->Prefix, 'ParentPrefix');
+			$item_type = $this->Application->getUnitOption($main_prefix, 'ItemType');
+			if (!$item_type) {
+				// no main config of such type
+				return false;
+			}
 			
 			// 1. get custom field information
-			$item_type = $this->Application->getUnitOption($main_prefix, 'ItemType');
 			$sql = 'SELECT FieldName, CustomFieldId
 					FROM '.TABLE_PREFIX.'CustomField
 					WHERE Type = '.$item_type.'
 					ORDER BY CustomFieldId';
 			$custom_fields = $this->Conn->GetCol($sql, 'CustomFieldId');
 			if (!$custom_fields) {
+				// config doesn't have custom fields
 				return false;
 			}