NSCollectionView Troubles

So I have been trying to get an NSCollectionView going for picking the puzzles in the desktop port for subaku. I found this article and like it says, the available documentation for NSCollectionView just seems lacking. What there is is mostly just Interface Builder connections and stuff, but going beyond that just seems to cause frustration. I want to be able to give it more customization that the bindings easily seem to do.

With the help of the above stack overflow page, I was able to get what you see above. But despite setting the selector, the button never actually calls it when it gets pushed. I am a bit confused here on what exactly I am missing.