In Pro Sites won't let me sign up without choosing categories

I setup wp-signup.php and first page asks for user name and email. on next page it asks for Sitename and description and block filled with several empty (unselectable0 pull down boxes under the heading "Site Categories" which it is not possible to do. When signup buttoin pressed. It stays on page and says "You must select at least 1 unique categories", so I can't signup? Waht gives here. Site categories plugin is not activated. How do I fix this? this should be mentioned somehwhere, ina manual or something.