SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6 pl2): Invalid SQL: SELECT username FROM bb1_users WHERE userid='1'' 
mysql error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''1''' at line 1 
mysql error number: 1064 
mysql version: 5.0.45-community 
php version: 4.4.9 
Date: 13.08.2008 @ 18:37 
Script: /board/filebase.php?userid=1' 
Referer: