Ken, thanks for your help. Turns out I was looking for the wrong thing, and the link I sent for my test server was actually working.

 

However, on the server where I really intend to use this, the upload button to start the upload dialogue does not even appear. In fact, the HTML stops loading at the point where "new PhpUploader()" is invoked. See the screenshot below:

 

This server is running PHP 5.1.6