not able to change zone groups

hi there!

when trying to change the zone group settings, an error shows up.

this is the log:

[Thu May 19 17:32:51 2011] [error] [client ::1] PHP Warning:  PDOStatement::execute(): SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`oscomm3`.`osc_zones_to_geo_zones`, CONSTRAINT `idx_z2gz_zone_id` FOREIGN KEY (`zone_id`) REFERENCES `osc_zones` (`zone_id`) ON DELETE CASCADE ON UPDATE CASCADE) in /var/www/oscommerce/osCommerce/OM/Core/PDOStatement.php on line 58, referer: http://localhost/oscommerce/index.php?Admin&ZoneGroups&EntrySave&id=1&zID=1
[Thu May 19 17:32:51 2011] [error] [client ::1] PHP Notice:  update osc_zones_to_geo_zones set zone_country_id = :zone_country_id, zone_id = :zone_id, last_modified = now() where association_id = :association_id in /var/www/oscommerce/osCommerce/OM/Core/PDOStatement.php on line 61, referer: http://localhost/oscommerce/index.php?Admin&ZoneGroups&EntrySave&id=1&zID=1

the data remains unchanged.

thank you
b