Domain Mapping Error Message

I just followed the instructions and added the Domain Mapping plugin. But I got this error message when I tried to log into the admin control panel.

WordPress database error Table 'level1.wp_domain_mapping' doesn't exist for query SELECT domain FROM wp_domain_mapping WHERE blog_id = '1' ORDER BY id LIMIT 1 /* domain mapping */ made by require_once, do_action, call_user_func_array, domain_map->build_cookie

I don't know if it matters but my WPMU installation is not in the root. It is in a subdiretory "1" as in website.com/1

Any help in figuring this out would be appreciated.