And just in case it is a validity period issue, here is a database query that finds all calendar keywords with a validity date less than 12/31/2017;
select OH_Client, OH_Name as 'Calendar', OKB_Name as 'keyword', OKB_ValidTo as 'Valid until'
FROM OH, OKB
WHERE OH_Idnr=OKB_OH_idnr
AND OKB_ValidTo < '2017-12-31 23:59:59:999'
order by 1, 2, 3;