问题 Bootstrap Select下拉列表自动向下移动

我是Bootstrap在IE11中选择用户。

当我用ajax填充数据并打开它然后它自动向下移动病房，当我选择任何值时，它没有被选中。如何删除此错误？

jQuery.ajax({
        url: base_url + "UserBusinesses/ajaxState/" + countryId,
        dataType: 'json',
        beforeSend: function () {
            $('#UserBusinessStateId').html('<option value="">Loding... </option>');
            $('#UserBusinessStateId').selectpicker('refresh');
            $('#UserBusinessCityId').html('<option value="">Select city</option>');
            $('#UserBusinessCityId').selectpicker('refresh');
        },
        success: function (obj) {
            var addHtml = '';
            addHtml += '<option value="">Select state</option>';
            $.each(obj, function (key, value) {
                var selected = "";
                if (selectedState == key) {
                    var selected = "selected='selected'";
                }
                addHtml += "<option value='" + key + "' " + selected + ">" + value + "</option>";
            });
            jQuery("#UserBusinessStateId").html(addHtml);

            $('#UserBusinessStateId').selectpicker('refresh');

        }
    });