thumbnail viewer not bringing up photo correctly

[MoePar]

1) Script Title: thumbnailviewer

2) Script URL (on DD): http://www.dynamicdrive.com/dynamicindex4/thumbnail.htm

3) Describe problem: I am using this on our car club site. I can make it work fine on home page, but it will not act the same on three of the other pages, even though I have used the same code, only changed the jpg name as it applies.
Our site is www.geocities.com/mountaingatewaymopars and the home page it works fine on the only jpg appearing, the other pages where the thumbnail viewer does not work are on member rides, more member rides & member activities.
I have the links to the css/js in headers identically in all three pages, like so:

<link rel="stylesheet" type="text/css" href="thumbnailviewer.css" />
<script language="javascript" type="text/javascript" src="thumbnailviewer.js">
/***********************************************
* Image Thumbnail Viewer Script- © Dynamic Drive (www.dynamicdrive.com)
* This notice must stay intact for legal use.
* Visit http://www.dynamicdrive.com/ for full source code
***********************************************/</script>

the home page where the code works for this is set up like this:

<a href="images/dales61wagon1.jpg" rel="thumbnail" title="Dale's 1961 Plymouth Wagon"><img src="images/dales61wagon.jpg" alt="Dale's 1961 Plymouth Wagon" width="250" height="89" border="0" /></a>

brings up image correctly & displays over the home page as it should.
When I do the same for the members rides, it displays the jpg on its own page, like a plain link. Here is how I have an example of two jpg's on that page:

<a href="images/donsdesoto1.jpg" rel="thumbnail" title="Don's DeSoto"><img src="images/donsdesoto.jpg" alt="Don's DeSoto" width="125" height="79" border="0" /></a>
<a href="images/toddsplymouth1.JPG" rel="thumbnail" title="Todd and Ruth's 1936 Plymouth Street Rod"><img src="images/toddsplymouth.JPG" alt="Todd's 1936 Plymouth Street Rod" width="125" height="83" border="0" /></a>

If I view the files (without going online) in a browser, it works (in firefox & ie - haven't tried others). I have tried clearing the cache while online with no change as to how it displays.

Any ideas anyone? I posted my website above so anyone can view the page source in its entirety.
Thanks in advance.

[MoePar]

Anyone have any ideas? Please?!?