descendantOf() causes js error in ie

Question

New to prototype, googled this trouble but didn't find any solution. Works fine in other browsers but alerts an error in ie

        Event.observe(document.body, 'click', function(evt) {
        var element = evt.target;
        if ('sign_in' != element.id  && 'customer_link'!= element.id && !element.descendantOf('sign_in') && !element.descendantOf('customer_link'))
        {$('sign_in').hide();$('customer_link').removeClassName('poped');}
    });

Answer 1

Use

var element = evt.element();

instead of

var element = evt.target;