Hard to tell without taking a look. Is the site somewhere on the WWW where I can look and see? PM me the URL if it is.
A common mistake is to set the website up on your hard drive with links to the images that specifically reference the location on your hard drive. For example <img=c:\webdev\myimage.jpg>. If you do that the page looks fine locally but the links fail when you upload the site to the web server because of the references to the hard drive. You would need to make sure that they just say something like <img=\webdev\myimage.jpg> so that they still find the images on the web server.
But as I said, hard to tell / can only guess without taking a look.
RC