You usually never add files to a project outside of Xcode, (meaning, simply place it in the folder) unless you want to have these sort of issues.
Try to remove it, restart the project (build and see that it has no broken links warnings), and drag the file to the navigator's folder in your open Xcode project.
Edit: Just to be clear, add through Xcode, not the Finder. Xcode should prompt you to either copy resource or not (check box).
I was going to suggest you Clean
the project, but I then noticed how you actually added the file.