Nib Name Not Appearing In Attributes Inspector

[Oral B]

Hey there. I'm working along with the book Beginning iPhone 3 Development, and am running into some issues on the "Pickers" app. I'm using Xcode 4.2, and I set it up exactly like they have it set up in their source code. All the code is the same, and all the outlet connections are the same. But, when I run my version, it launches a black screen, and the debugger says "Applications are expected to have a root view controller at the end of application launch."

There version in the source code runs just fine, and mine looks identical to it, but for some reason mine just won't run. I've Googled this issue and people have a bunch of workarounds, but I feel like there is something really simple in IB that I'm not seeing.

Any help would be great, thanks.