reminder on validations in ajax mvc razor

 Order IS important and can stop the client side vlidation working if not in this order.
    <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" />
    <script src="@Url.Content("~/Scripts/jquery-1.5.1.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery-ui-1.8.11.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>


        [Required]
        [StringLength(20, MinimumLength = 4)]
        [Display(Name = "User Name")]
        [RegularExpression(@"(\S)+", ErrorMessage = "White space is not allowed")]
        [ScaffoldColumn(false)]
        public string UserName { get; set; }

        [Required]
        [StringLength(18, MinimumLength = 0)]
        [Display(Name = "First Name")]
        public string FirstName { get; set; }
        [Required]
        [StringLength(18, MinimumLength = 0)]
        [Display(Name = "Last Name")]
        public string LastName { get; set; }

            <div class="editor-label">
                @Html.LabelFor(model => model.FirstName)
            </div>
            <div class="editor-field">
                @Html.TextBoxFor(model => model.FirstName)
                @Html.ValidationMessageFor(model => model.FirstName)
            </div>
           
            <div class="editor-label">
                @Html.LabelFor(model => model.LastName)
            </div>
            <div class="editor-field">
                @Html.TextBoxFor(model => model.LastName)
                @Html.ValidationMessageFor(model => model.LastName)
            </div>
            <div class="editor-label">
                @Html.LabelFor(model => model.UserName)
            </div>
            <div class="editor-field">
                @Html.TextBoxFor(model => model.UserName)
                @Html.ValidationMessageFor(model => model.UserName)
            </div>