javascript Error

Hy guys

i have this error

uncaught exception: [Exception... "Could not convert JavaScript argument" nsresult: "0x80570009 (NS_ERROR_XPC_BAD_CONVERT_JS)" location: "JS frame :: http://www.tgi.com.pt/merdo/scroll/ :: anonymous :: line 435" data: no]

the problem is this code

<script type="text/javascript">
var gal = {
init : function() {
if (!document.getElementById || !document.createElement || !document.appendChild) return false;
if (document.getElementById('gallery')) document.getElementById('gallery').id = 'jgal';
var li = document.getElementById('jgal').getElementsByTagNa me('li');
li[0].className = 'active';
for (i=0; i<li.length; i++) {
li[i].style.backgroundImage = 'url(' + li[i].getElementsByTagName('img')[0].src + ')';
li[i].style.backgroundRepeat = 'no-repeat';
li[i].title = li[i].getElementsByTagName('img')[0].alt;
gal.addEvent(li[i],function() {
var im = document.getElementById('jgal').getElementsByTagNa me('li');
for (j=0; j<im.length; j++) {
im[j].className = '';
}
this.className = 'active';
});
}
},
addEvent : function(obj, type, fn) {
if (obj.addEventListener) {
obj.addEventListener(type, fn, false);
}
else if (obj.attachEvent) {
obj["e"+type+fn] = fn;
obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
obj.attachEvent("on"+type, obj[type+fn]);
}
}
}

gal.addEvent(window,'load', function() {
gal.init();
});
</script>

Code (markup):

I thin this is a conflict between fancybox plug in and the script above

http://www.tgi.com.pt/merdo/scroll/

I really need help...

Thanks

 

Not sure if this is related to the problem, but I found two instances of .getElementsByTagNa me('li');
That ain't right

 

However I can solved the problem with another script. By the way i have a new problem. Now i have two pages, separately, and work without problems, but i need these two pages in one file. But my idea is to have a index page with buttons that import (load content) these two pages. I think the problem is a conflict between fancybox...because the files are functioning without problems in separately. there is some different way to do this without ajax? What is your suggestion?

w w w.tgi.com.pt/merdo/scroll/indexaa.html
w w w.tgi.com.pt/merdo/scroll/indexa.html
w w w.tgi.com.pt/merdo/scroll/index.php