jquery dialog not centering?

http://stackoverflow.com/questions/3856026/jquery-dialog-not-centering ~ Rubens Mariuzzo (www.mariuzzo.com)

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/base/jquery-ui.css">
<div id="editDialog">     
            
                <div id="editDialogContent" style="font-size: 65%;">
                   
                    
                    <div id="editItemDialog" >
                        <table style="width: 100%">
                            <tr>
                                <td>
                                    <label id="closeEditItemDialog" style="float: right;">[close]</label>
                                </td>   
                            </tr>    
                        </table>
                        
                    </div>
 
                
                    <table style="width: 100%;">
                    
                        <tr id="editDialogRow_1">
                            <td class="labelHeaders">
                                <label>Repair Date:</label>
                            </td>
                            <td class="valueCells">
                                    <label class='labelValue' id="lblRepairDate" ></label>
                            </td>
                            <td>
                                    <label class='labelEdit'>(edit)</label>
                            </td>
                            
                            
                            <td class="labelHeaders">
                                <label>Wrong Repair Ind:</label>
                            </td>
                            <td class="valueCells">
                                 <input id="chkbWrongRepairInd" name="chkbWrongRepairInd" type="checkbox" />
                            </td>
                            <td>
                            
                            </td>
                            
                            <td class="labelHeaders">
                                <label>Currency:</label>
                            </td>
                ...

CSS

#loadingScreen {
    background: url(Images/loading.gif) no-repeat 5px 8px;
    padding-left: 25px;
}

.loadingScreenWindow .ui-dialog-titlebar-close {
        display: none;
}
.labelEdit 
{
    text-decoration: underline; 
    cursor:pointer;
}
.labelValue
{
    display:inline-block;
}
.labelHeaders
{
    white-space: nowrap;
}
.valueCells
{
    white-space: nowrap;
    border: solid 1px white;
}
#editItemDialog{
    margin: 0 auto;
    position: absolute;
    width: 60%;
    height: 70px;  
    background-color: red;
}

JavaScript

$('#editItemDialog').hide();
$('#closeEditItemDialog').click( function() {
    $('#editItemDialog').hide('slow');
});

$('.labelEdit').hover( function() {
                   $(this).parent().prev().css('border', 'solid 1px blue');    
                 }, function() {
                    $(this).parent().prev().css('border', 'solid 1px white'); 
});


$('.labelEdit').click( function() {
    
       $('#editItemDialog').show('slow');
    
});