jqModal causing error on "Enter"-link: "h is undefined"

Because Thickbox nor NyroModal seem to work in my case, I decided to use the jqModal-method for the Disclaimer dialog box. It does the job, but when I hit the default button "Enter" in the box, nothing happens. The box remains on the black overlay. When I refresh the browser, it goes immediately to the page that was overlaid by the Disclaimer box though. So somehow the cookie was written succesfully, but the Disclaimer dialog box won't go away with manually refreshing the page.

What could be causing this behaviour?

This is what I found in the console:

Error: h is undefined
Source: domain.be/my-page
Line: 54

<script type="text/javascript">
<!--//--><![CDATA[//><!--
function WriteCookie(nom, valeur){
var argv=WriteCookie.arguments;
var argc=WriteCookie.arguments.length;
var expires=(argc > 2) ? argv[2] : null;
var secure=(argc > 5) ? argv[5] : false;
var domain=(argc > 4) ? argv[4] : null;
document.cookie=nom+"="+escape(valeur)+
((expires==null) ? "" : ("; expires="+expires.toGMTString()))+
("; path=/")+
((domain==null) ? "" : ("; domain="+domain))+
((secure==true) ? "; secure" : "");}
if (ReadCookie("disclaimerShow") == null) {$(document).ready(function(){$('#disclaimer').jqm({ajax:'/nl/disclaimer', overlay:90, modal:true}).jqmShow();});}
//--><!]]> // <---------------------------------- THIS IS LINE 54
</script>