Unable to edit user levels in WP1.0.2

I have a user on my blog created when I imported entries from Movable Type. This user is showing up in the user panel under the admin account but I am unable to change the level of this user. It remains at 0 no matter how many times I click on the “+”.
How can I change the user level? I am comfortable with editing things through PHPMyAdmin, but I need to know where to look first.