Cheatin', uh? message in Membership

I am getting the "cheatin, uh?" message in the Membership plugin, when I try to add more than 3 levels. I have WP 3.5.2 and the latest plugin, installed a couple of days ago. The tables looked good, but I chose "repair tables" anyway, just in case. I deactivated the plugin, wanted to delete and reinstall; there is no "delete" link there! Stuck.