PDOException: SQLSTATE[42S02]: Base table or view not found: 1146 Table '[database].semaphore' doesn't exist: SELECT expir

PDOException: SQLSTATE[42S02]: Base table or view not found: 1146 Table '[database].semaphore' doesn't exist: SELECT expire, value FROM {semaphore} WHERE name = :name; Array ( [:name] => variable_init ) in lock_may_be_available() (line 167 of /var/www/html/sexxldeiphonecom/includes/lock.inc).

这个是什么原因。