Across the bottom of the page at http://www.aptcoweb.com/Forms.htm they work fine.
In the version in progress, http://www.aptcoweb.com/test.htm they don't. I keep staring at the code and can't find the problem. This came from a library item and the folder structure has been modified but I don't see how that would effect it.
Somehow your rollover images were all named '999'.
On the page that works, each of them have the right name.
Aha, thanks! Something went awry in copy and paste.
Recreating them all fixed it.