during wp import, error appeared with $old_cat_ids

here are the logs : 
[Thu Jul 11 11:10:06 2013] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: old_cat_ids in /var/www/dotclear/plugins/importExport/inc/class.dc.import.wp.php on line 673, referer: http://localhost/dotclear/admin/plugin.php?p=importExport&type=import&module=dcImportWP
[Thu Jul 11 11:10:06 2013] [error] [client 127.0.0.1] PHP Fatal error:  Call to a member function isEmpty() on a non-object in /var/www/dotclear/plugins/importExport/inc/class.dc.import.wp.php on line 673, referer: http://localhost/dotclear/admin/plugin.php?p=importExport&type=import&module=dcImportWP