jQuery overlay not working in IE6, Opera

I've been scratching my head for hours trying to figure this out. I have this page: http://173.203.72.190/default.aspx. On clicking 'Any Cuisine', a sort of overlay is supposed to open.

It works fine in nearly all browsers except IE6 and Opera. In IE6 and Opera, the jQuery 'overlay' won't open.

Anybody have any ideas why this might be?

Edit: The code triggering the overlay is below:

$("a#zoneListLink").click(function() { 

    var listTop = $(this).css("top");
    var listLeft = $(this).css("left");

    var api = $("a#zoneListLink").overlay({api: true, close:'div.close', top: listTop, left:listLeft, onLoad:function() { $(document).click(function() { api.close(); } ); },
    onClose:function() { $(document).unbind("click"); } }).load();

});

There is a bug or incompatibility inside the jQuery overlay effect. It's hard to find because Opera's behaviour makes more sense, but breaks the script's buggy expectations..

First, compare the output of this command in Opera and for example Firefox:

javascript:alert(getComputedStyle(document.getElementById("cuisineListLink"),'').top);

Opera gives you the top position of the cuisineListLink in pixels. Firefox says "auto".

Now, in combined.js look for this code (wrapped by me):

if(typeof t=="string"){
    t=t=="center"?Math.max((n.height()-q)/2,0):parseInt(t,10)/100*n.height()
}

I have no idea why it does "parseInt(t,10)/100*n.height()", but it looks like this code expects either the string "center" (to do vertical centering of the layer) or a number. When Opera passes in a string like '310px', the script will extract the integer, divide it by 100 (i.e. 3.1) and multiply it with the height of your browser window (?!). Net effect is that the overlay is positioned carefully outside of the screen - 3 screen heights down.

In Firefox, we get to this line and the t variable is the string 'auto'. The script tries parseInt() which returns 'Not a Number', NaN, and proceeds to divide by 100 and multiply with window height - which of course keeps returning NaN. Then it positions the overlay at NaNpx which the browser will simply ignore as a bogus value. You will find a warning to that effect in Firefox's error console.

I'd recommend using a different overlay plugin (or perhaps a newer iteration?) because this code doesn't make much sense.