CKeditor bug: styles and class

Hello,

I've got a problem. I installed CKeditor. Looks good and works great, except for a bug(?).

I wanted to change the styles. And I changed the styles in the plugin stylescombo/styles/default.js

I changed it to:
CKEDITOR.addStylesSet('default',[{name:'Sub',element:'h2'},{name:'Quote',element:'span',attributes:{class:'greenquote'}}]);

In Firefox 3.5 it works good. But in IE7, IE6, Safari for windows, safari on Mac it don't work good.
I get a javascript error and when i click the dropdown for styles it will not show the styles. Does anyone knows this problem? And how to fix this?

Errors (translated):
error1: Id, chars or number is expected
error2: length is empty or not an object

Does anyone knows a solution?

The problem is because I add the 'class' atrribute. That is not working for IE6/7, etc.
In Firefox no problem. It continues to work.