Backspace key not working to clear search filter

Hi.
I'm not sure what I'm missing here, but in my application, entering text into the search field seems to disable the backspace key - I can't delete the content of the search field unless I select the content or move the cursor and use the Delete key instead.

I use jquery Dialog to display the table in:

<div id="dialog"></div>

My included file versions:

<link href="/common/jquery-ui/css/smoothness/jquery-ui-1.9.1.custom.min.css" rel="stylesheet">
<link href="/common/dataTables/css/jquery.dataTables.min.css" rel="stylesheet">
<script src="/common/jquery-ui/js/jquery-ui-1.9.1.custom.min.js"></script> 
<script src="/common/js/jquery.dataTables.min.js"></script>

My js code is as follows:

var $dialog;  // holds dialog box

$(function()
{
    $dialog = $('#dialog');
    if ($dialog.length == 0)
    {
        $('#MainContent').append('<div id="dialog"></div>');
        $dialog = $('#dialog');
    }
    
    // init dialog box
    $dialog.dialog({
        title: 'Family Selector',
        minWidth: 600,
        height: 'auto',
        position: { my: "center top", at: "center top", of: window },
        modal: true,
        autoOpen: false,
        open: function(event, ui) {
            $('.ui-widget-overlay').bind('click', function(){ $dialog.dialog('close'); });
        }
    });
});

function OpenFamilySelector()  // open dialog box with ajax driven list of families
{
    $dialog.empty().html('<table id="famTable" cellspacing="0" width="100%"><thead><tr><th>Select</th><th>Family ID</th><th>First Name</th><th>Last Name</th></tr></thead><tfoot><tr><th>Select</th><th>Family ID</th><th>First Name</th><th>Last Name</th></tr></tfoot></table>');
    $dialog.dialog('open');
    $('#famTable').dataTable({
        "ajax": '/ajax.php?act=fl',
        "columnDefs": [
            {
                "render": function (data, type, row)
                {
                    return '<input type="checkbox" class="fchk" value="' + row[1] + '">';
                },
                "orderable": false,
                "targets": 0
            }
        ],
        "order": [[1, "asc"]]
    });
}

I have no idea what could cause the backspace key to malfunction here...

Thoughts?

Thanks!