Displaying post content within lightbox

First of all thanks for the great and simple plugin. I am having a tricky issue over here trying to display some content within a lightbox. What I did was create a custom post type with a template containing just the the_content(). The coding in the template is fine, and the post displays normally and even when using FancyBox. The thing is I would like to use the prettyPhoto script to display the content. From what I remember, when I first tested this out with a link to http://www.google.com last week everything was working fine. I was able to tweak the settings for the prettyPhoto and it displayed the content exactly how I wanted. Now today I tried to implement it with a link to actual content on my site and it won’t work. I am getting an error message saying “Image cannot be loaded. Make sure the path is correct and image exists”. I think that last week I might have been doing something with an iframe to get it to work, but now I can’t remember.

Any ideas?

https://ww.wp.xz.cn/plugins/responsive-lightbox/