Problem Loading WordPress Core into an External File

A few weeks ago, I created the History Manager plugin. It worked fine on my site, but one person who downloaded it from the repository is having a strange problem with it.

It is an AJAX plugin, so the file contains the main plugin file that prints the text to the screen for the widget, then another PHP file that is called by Javascript to get the information, then display it back on the page. You can see how it works on my site.

Unfortunately, when it is used on this person’s site, it does not load the WordPress core as it is supposed to (done using an include function), meaning it doesn’t return anything to the wp_list_pages and similar functions. What’s also strange is the fact that there are no errors generated in this process.

I sent another test copy to see if WordPress was being loaded at all, and I was able to retrieve the get_bloginfo information, but still none of what the plugin was supposed to do. You can see this at this site.

Anybody have any idea for why this isn’t working? Feel free to take a look at the plugin’s source to see if I did something wrong.