Newbie Issue: isDescendantOf: error

FROM : Jamie Phelps
DATE : Thu Feb 14 18:29:03 2008

I am working through Aaron Hillegass's book currently in Chapter 10: 
Using the Defaults, and I am getting this error when trying to bring 
up my Preferences panel.

[PreferenceController isDescendantOf:]: unrecognized selector sent to 
instance 0x103eb70

My troubleshooting got me as far as realizing there is a problem with 
the line

self = [super initWithWindowNibName:@"Preferences"];

but I'm not sure where to go from there. I'm sure this is a newbie 
problem, but I'm stumped. If anyone can offer pointers that'd be 
great. Also, if you can enlighten me as to how I could have figured 
this out on my own, that would be awesome. You know, teach a man to 
fish and all that.

Thanks,
Jamie