I'm wondering if this is a WP issue. Mine was working and then all of a sudden stop working, done it twice on me.
Setup a 2nd WP site today just to see if it would work. Only thing installed was the Akismet plugin and a wooTheme. It was working fine. Click on an image in a post and it brought up the shadowbox just fine. Added some more stuff, seemed to be still working. Went a way for a couple hours. Came back started tweaking WP some more and now it doesn't work. When I click on an image in a post it goes to a seperate page of it's own with room for comments. If I click it there it THEN goes into Shadowbox but only one image.
This blog is just being setup and has only 1 post at the moment. It worked originally but not now.
Installed both the latest active Shadowbox JS and the developmental version posted above but no dice.
I have it on another site, current WP version and it works fine. I can't see any config differences other than theme between the two. But the two themes I've tried on this latest install don't work.