Drag-and-drop - object not moving with the mouse on IE7

[scf1984]

I have this code creating an object to drag-and-drop:

window.onload = function()
{
    var dragObject = document.createElement('DIV');
    dragObject.id = 'dragObject';
    dragObject.style.cssText = 'position:absolute;display:none;';
    document.body.appendChild(dragObject);
}

Then, onmousedown:

function dragme(obj)
{
    var dragObject = document.getElementById("dragObject");
    while (dragObject.hasChildNodes())
    {
        dragObject.removeChild(get_lastchild(dragObject));
    }    
 
    dragObject.appendChild(obj.cloneNode(true));
    dragObject.style.display = 'block';
    dragObject.style.visibility = 'visible';
    dragObject.firstChild.style.display = 'block';
    dragObject.firstChild.style.visibility = 'visible';
}

And these functions to update the object's coordinates:

function mouseMove(ev)
{
    ev= ev || window.event;
 
       var dragObject = document.getElementById("dragObject");
        if(dragObject.hasChildNodes()){
        dragObject.style.position = 'absolute';
        dragObject.style.left = mouseCoords(ev).x;
        dragObject.style.top = mouseCoords(ev).y;
    }
}
 
function mouseCoords(ev)
{
    if(ev.pageX || ev.pageY){
        return {x:ev.pageX, y:ev.pageY};
    }
    return {
        x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,
        y:ev.clientY + document.body.scrollTop  - document.body.clientTop
    };
}

But still, in IE7, I don't get to see the object moving with the mouse when I try to drag an <tr> element - it is hidden somewhere.

Please, advise...

[scf1984]

p.s. - It wroks great on FireFox, but not on IE7 :(