Почему в таблице не работает valign="middle" ???(*теги ниже)

<style>
div.popup, div.popup_active {
position: fixed;
z-index: 0;
display: none;
font-size: 11px;
padding: 3px;
color: #666;
background: #FFFFFF;
border: 1px solid #333333
}
div.popup_active { display: block }
</style>
<script>
function show (evt, id) {
var evt = evt || window.event;
var o = evt.target || evt.srcElement;
var f = document.getElementById('cur_popup_note');
if (f == null) {
f = document.createElement('div');
f.setAttribute ('id', 'cur_popup_note');
f.setAttribute ('style', 'progid:DXImageTransform.Microsoft.Alpha(opacity=100); '+ 'opacity: 1; display: block; top: 0px; left: 0px;');
f.setAttribute('class', 'popup');
document.body.appendChild(f);
}
f.opacityFilter = 0;
f.innerHTML = ''+ '' + document.getElementById(id).innerHTML + '';
f.className = 'popup_active';
f.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(opacity=' + (f.opacityFilter * 100) + ');';
f.style.opacity = f.opacityFilter;
f.style.display = 'block';
f.style.top = ((screen.height - 200)/2) + 'px';
f.style.left = (((screen.width - 400)/2) - 20) + 'px';
window.setTimeout('animate()', 50);
evt.cancelBubble = true;
return false;
}
function hide() {
var div = document.getElementById('cur_popup_note');
if (div != null) {
div.className = 'footnote_new';
div.style.display = 'none';
}
return false;
}
function animate() {
var f = document.getElementById('cur_popup_note');
f.opacityFilter += 0.1;
f.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(opacity=' + (f.opacityFilter * 100) + ');';
f.style.opacity = f.opacityFilter;
if (f.opacityFilter<1) window.setTimeout('animate()', 50);
}
</script>



<p>текст</p>