date browser bug?

First, sorry for my english.
I'm trying to make data browser for events archive. My events is CCK nodes with Date fields: "from" & optionally "to" parts. I'm looked at default date browser view and make similar thing (see attached view-date-arg.gif).
But i always get empty result. SQL in preview looks like:

SELECT node.nid AS nid,
   node_data_field_date.field_date_value AS node_data_field_date_field_date_value,
   node_data_field_date.field_date_value2 AS node_data_field_date_field_date_value2,
   node.type AS node_type
 FROM node node 
 LEFT JOIN content_type_event node_data_field_date ON node.vid = node_data_field_date.vid
 WHERE ((node.status <> 0) AND (node.type in ('event')) AND (node.moderate = 0))
    AND (((DATE_FORMAT(STR_TO_DATE(node_data_field_date.field_date_value, '%Y-%m-%dT%T'), '%Y-%m') <= '2008-10' AND DATE_FORMAT(STR_TO_DATE(node_data_field_date.field_date_value2, '%Y-%m-%dT%T'), '%Y-%m') >= '2008-10')) OR ((DATE_FORMAT(STR_TO_DATE(node_data_field_date.field_date_value, '%Y-%m-%dT%T'), '%Y-%m') <= '2008-10' AND DATE_FORMAT(STR_TO_DATE(node_data_field_date.field_date_value2, '%Y-%m-%dT%T'), '%Y-%m') >= '2008-10')))
   ORDER BY node_data_field_date_field_date_value ASC

I think checking start date for "<= arg" and end date for "=> arg" at same time is buggy.