Anyone have any ideas why scrollTop isn't working in IE?

It works in Chrome fine, and I don't know about firefox. (The idea of this script is to have an autoscrolling page that resets once it hits the bottom of the page)

function getheight() {



                var myWidth = 0,

            myHeight = 0;

             if (typeof (window.innerWidth) == 'number') {

                    //Non-IE

                    myWidth = window.innerWidth;

                    myHeight = window.innerHeight;

                } else if (document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {

                    //IE 6+ in 'standards compliant mode'

                    myWidth = document.documentElement.clientWidth;

                    myHeight = document.documentElement.clientHeight;

                } else if (document.body && (document.body.clientWidth || document.body.clientHeight)) {

                    //IE 4 compatible

                    myWidth = document.body.clientWidth;

                    myHeight = document.body.clientHeight;

                }

                var scrolledtonum = window.pageYOffset + myHeight + 2;

                var heightofbody = document.body.offsetHeight;

                if (scrolledtonum >= heightofbody) {

                    document.body.scrollTop(0, 0);

                }

            }



            window.onscroll = getheight; 



            function func() {

                window.document.body.scrollTop++;

            }



            window.document.onmouseover = function () {

                clearInterval(interval);

            };



            window.document.onmouseout = function () {

                interval = setInterval(func, 20);

            };



            var interval = setInterval(func, 20);