I think it’s because you can’t use lightbox with the other libraries that you are using. I don’t think it works with scriptaculous or prototype. I don’t remember which one. If you want to figure it out, delete one of those calls from your header and test the lightbox. To use a lightbox effect that does work with those libraries, google shadowbox. Same kind of thing, even works with rel="lightbox" or rel="shadowbox" both will work. I like it because if you have lightbox all in your code, you don’t need to change it.
yes, that’s right. I couldn’t remember. In any case, I just had this problem myself because I have a website that has a lot of pictures and I had a jquery slider and needed the lightbox to work. It won’t work with the slider. I had the coda slider working on the site but not the lightbox. I had to use the shadowbox to get it working. Take a look