Discuz! info: MySQL Query Error

Time: 2008-10-11 6:39am
Script: /bbs/index.php

SQL: INSERT INTO cdb_sessions (sid, ip, ipbanned, status, username, lastactivity, groupid, styleid, action, fid, tid)
VALUES ('trnBT2pr', '38.103.63.60', '0', 'Guest', '', '1223678366', '1', '1', '0', '', '')
Error: Incorrect integer value: '' for column 'fid' at row 1
Errno.: 1366

Similar error report has beed dispatched to administrator before.