Javascript error when clicking an image to view full size

[Marty McFly]

Here is the gallery that I'm working on:
http://coogsports.net/imagegallery/displayimage.php?album=lastup&cat=0&pos=0

This pic is pretty big and should resize when it's clicked, but there is a javascript error and nothing happens.  I haven't done anything to the original coding of this, except for change the theme, so I'm not sure what went wrong here.  If anyone has any advice it would be appreciated.

[Nibbler]

http://coppermine-gallery.net/demo/cpg14x/docs/faq.htm#noFullsizePopup

[Marty McFly]

That did it, thanks!