Frustrating problem with shader-based code.

[the_hoser]

I'm trying to get my feet wet with LWJGL (and modern opengl at the same time) using the tutorials at:

http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html

I'm currently working on chapter 2.  Instead of rendering the interposing images fading back and forth, I just get a black screen.  I've combed over the code and I can't figure out where I'm going wrong.

I normally don't post on forums asking for help, but this is driving me a little bit batty.  I've refactored the code into a single file and pasted it at:

http://pastebin.com/pEdErRMY

The images can be found at:

http://duriansoftware.com/joe/media/gl2-hello-1.png
http://duriansoftware.com/joe/media/gl2-hello-2.png

Thank you for your time.