Problem Building Interface Builder Plugin for Custom NSView Class

Question

I am trying to get a plugin working for Interface Builder.

Interface Builder version 3.2. XCode 3.2.1 Mac OS X 10.6.2 MacBookPro5,3

I follow the Quick Start directions on the Apple Developer Site:

http://developer.apple.com/mac/library/DOCUMENTATION/DeveloperTools/Conceptual/IBPlugInGuide/Plug-inQuickStart/Plug-inQuickStart.html

and I keep getting the error:

'The bundle “MyIBPlugin” couldn’t be loaded because it is damaged or missing necessary resources.'

when I try to add the built plugin to Interface Builder via the IB Preferences dialog. I have verified three separate times that I'm performing each of the steps in the Quick Start.

Any ideas where I might be going wrong? Has anyone successfully built a plugin for Interface Builder 3.2.1?