XCode Can't Find Headers With Certain User Account

I've been dabbling around with building out a sample project using the SoundCloud APIs.

Following these directions explicitly:

http://developers.soundcloud.com/docs/api/ios-quickstart

Under the primary user account on my iMac (under which I've written thousands of lines of Objective-C quite sucesfully), I cannot get this tutorial to work. I import all the git submodules, add the files to my project, link the libraries and set the Header Search Paths. I've done it no less than a dozen times, no way I've missed a step - I just can't get the headers to be recognized (eg, code complation and ultimately building doesn't work).

My project build fails with the first line I reference the 3rd-party SDK:

#import "SCUI.h"

It basically appears as though XCode can't see the headers of the libraries I've added.

Now, if I go in to a fresh user account on my Mac, launch XCode, and follow the exact same procedures, it works exactly as described in the tutorial, perfectly.

I've tried obvious things like deleting XCode prefs(~/Library/xcode*), destroying derived data/cleaning (honestly i've recreated the project a dozen times, with different names, etc, so it's not a build/derived data issue).

How can I "reset" the instance of XCode that is running under my primary user account? Can anyone explain this phenomena?