If your missing the "site_cron" table simply run this sql
CREATE TABLE `site_cron` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`prio` int(11) NOT NULL DEFAULT '5',
`enabled` enum('0','1') NOT NULL DEFAULT '1',
`scriptfile` varchar(50) NOT NULL,
`last_exec` int(11) NOT NULL,
`exec_every`...