Any other info you can provide? Version number? What isn't working? Do you have other addons? Did you turn them off and then try with only nUI turned on?
says last updated 3/31 the middle part,where the minimap and raid UI should go isnt there. it's blank. also the area to the right of that where recount and other display options dont show up. the hud doesnt apear at all,but the chat box is fine.
Looks like you don't have the new version designed for 3.1. It's listed in the announcements section that you need to sign up and once accepted you will have access.