Unable to select value of dropdown using jQuery

I am trying to set value in "select" control using jQuery. It is observed that sometime it select value correctly and sometime it does not select value.

I have an xml document, below code pull xml value and set it to dropdown list (html select) This is my jQuery Bock.

var select = '#' + formname + ' select[binding="true"]'; //here select those dropdown whose binding property is true.
$(select).each(function (i) {
    var bindName = $(this).attr("DataMember");
    if (bindName != '') {
        $xmlNode = $xml.find(bindName);
        if ($xmlNode != null) {
            var value = $xmlNode.text();
            if (value == "0")
                value = '';
            $(this).val(value); //here actual value is set as per xml value
        }
        else
            $(this).val('');
        $(this).trigger("change");
        $(this).trigger("chosen:updated");
    }
});

Some time this code works some time it does not work. can anybody let me know what's the problem with this code.