datepicker bug

HTML

<link rel="stylesheet" href="https://iis6-02.cevi.be/eloket/Sites/TnrSite6/jquery-ui-themeroller.css">
<body>
<fieldset>
    <legend></legend>
    <label for="theFirstField">First Field</label>
    <input type="text" id="theFirstField"/>
</fieldset>
<fieldset>
    <legend>default behavior</legend>
    <label for="theDate1">Date</label>
    <input type="text" style="width: 88px;" class="datepicker" id="theDate1" size="10" />
    <input type="text" id="theNextField1"/>
</fieldset>
<fieldset>
    <legend>fix taborder</legend>
    <label for="theDate2">Date</label>
    <input type="text" style="width: 88px;" class="datepicker" id="theDate2" size="10" />
    <input type="text" id="theNextField2"/>
</fieldset>
</body>

JavaScript

$(document).ready(function () {
        $.datepicker.setDefaults($.extend({},
            {
                         changeMonth: true,
                         changeYear: true,
                         showStatus: true,
                         dateFormat: 'dd/mm/yy',
                         duration: 'fast',
                         yearRange: '1890:2100'
 
            }
            )
        );

        $("#theDate1").datepicker({}); 
        $("#theDate2").datepicker({
            onSelect: function () {
                document.all ? $(this).get(0).fireEvent("onchange") : $(this).change();
                this.focus();
            },
            onClose: function () {
                 this.focus();
            }
        });
     });