我的函数没有返回所有选中的值

我正在填充Ajax调用上的复选框列表，我正在尝试获取选中了哪些复选框，但我只得到了第一个值。如果我做错了什么，请帮助我。

我的网页：

<%@ Control Language="C#"Inherits="System.Web.Mvc.ViewUserControl<EmsAdmin.Models.User>" %>
<%= Html.ValidationSummary("Edit was unsuccessful. Please correct the errors andtryagain.") %>
<% using (Html.BeginForm(null, null, FormMethod.Post, new { name = 
"VerficationForm", id = "VerficationForm" }))
 {%>
<%= Html.AntiForgeryToken() %>
<%: Model.Id %>
<h2>Go For All / Individual Brands</h2>
<p>
<input type="checkbox" id="checkBoxAllSelect" class="checkBoxAllSelect" value="All" />
All
<br />
<input type="checkbox" id="checkBox1Individual" class="checkBox1Individual" 
 value="Individual" />
 Individual
<br/>
 <input type="button" value="GetBrands" class="getBrands" />
</p>
<hr />
<h2>Multi Select Brands If Required:</h2>
 <div id="checkboxes" class ="divNewBrandsList">
 </div>
 <hr />
<h2>Countires For Each Brand:</h2>
<div id="checkboxescountries" class="divNewCountriesList">
 </div>
 <hr />
 <% } %>

脚本：

 <script type="text/javascript">
 $('.getBrands').hide();
function myBrandsfunction() {
    var selectedBrands = "";
    var manu = "";
    var input = "";
    $("#checkboxes input:checked").each(function () {
        manu = $(this).val();
        alert("Brand value:" + manu); // Here I am getting only one Selected checkbox but not all.
        selectedBrands = selectedBrands + "," + manu;
        alert("Selected brands:" + selectedBrands);
        var productInput = "";
        var myUrl = "/Countries/GetCountiresForManufacturer/" + selected + "/" + input;
        $.ajax({
            url: myUrl,
            type: 'get',
            success: function (data) {
                productInput = data;
                $(".divNewCountriesList").html(productInput);
            }
        });
    });
}

控制器：

    /// <summary>
    /// GetBrands for Organisation
    /// </summary>
    /// <returns></returns>
    [Authorize(Roles = "Administrator")]
    [AcceptVerbs(HttpVerbs.Get)]
    public string GetBrandsForOrganisation(string organisation)
    {
        var sb = new StringBuilder();
       // var brandsList = new List<String>();
        if (organisation == null)
        {
            return "";
        }
        else
        {
            var corporation = _corporationRepository.GetCorporationByName(organisation);
            if (corporation != null)
            {
                // Get Manufactuerers 
                var brands = _corporationManufacturerRepository.GetAllManufacturersForCorporation(corporation.Id);
                sb.Append("<div id = '"" + organisation + "'">");
                foreach (var brand in brands)
                {
                    sb.Append("<input id ='"" + brand.Manufacturer.Id +
                              "'" type='"checkbox'" class='"checkboxBrand'" value='"" +
                              brand.Manufacturer.Description + "'"/>" + brand.Manufacturer.Description);
                    sb.Append("<br />");
                }
                sb.Append("<br />");
                sb.Append("</div>");
            }
        }
        sb.Append("<input type='"button'" value='"GetCountries'"  onclick = '"myBrandsfunction()'"class='"brands'"/>");
        return sb.ToString();
    }