Handling multiple submit buttons in MVC with Kendo tab strip

Question

I have a Kendo tab strip. On each tab is a view with a submit button. I'm having trouble handling multiple submit buttons. I'm following the answer on this post by @mkozicki.

But I can't get to work. The line

var value = controllerContext.Controller.ValueProvider.GetValue(keyValue);

always returns null. Can someone either explain why this answer doesn't work or provide another way of handling multiple submit buttons within a tab strip?

Notes:

• I also tried code similar to what's at this page (I didn't bookmark my original source, but the code is similar), but it didn't work either.

• I tried both AllowMultiple equals true and false, both product the same result: the value was null

ClsActionMethodSelector.cs (creates the multiple button attribute)

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class MultipleButtonAttribute : ActionNameSelectorAttribute
{
    public string Name { get; set; }
    public string Argument { get; set; }

    public override bool IsValidName(ControllerContext controllerContext, string actionName, MethodInfo methodInfo)
    {
        var isValidName = false;
        var keyValue = string.Format("{0}:{1}", Name, Argument);
        var value = controllerContext.Controller.ValueProvider.GetValue(keyValue);

        if (value != null)
        {
            controllerContext.Controller.ControllerContext.RouteData.Values[Name] = Argument;
            isValidName = true;
        }

        return isValidName;
    }
}

AdminCustomerEdit.cshtml (the Kendo tab strip)

@using (Html.BeginForm("AdminCustomerEdit", "Admin", new {compI = ViewBag.compId}))
{
                @(Html.Kendo().TabStrip()
                      .Name("AdminCustomerEditTabs")
                      .Items(items =>
                      {
                          items.Add()
                              .Text("Notes")
                              .HtmlAttributes(new {@class = "tab"})
                              .Content(Html.Action("AdminCustomerNotes", "Admin", new {customerID = Model.CompID}).ToString())
                              .ContentHtmlAttributes(new {@class = "tab-content"});
                          items.Add()
                              .Text("Contracts")
                              .HtmlAttributes(new { @class = "tab" })
                              .Content(Html.Action("AdminCustomerContracts", "Admin", new { customerID = Model.CompID }).ToString())
                              .ContentHtmlAttributes(new { @class = "tab-content" });
                      })
                      )
}

AdminController.cs

    [HttpPost]
    [MultipleButton(Name = "action", Argument = "CustomerNotes")]
    public ActionResult AdminCustomerNotesSubmitEdit(CompanyNotes model)
    {
    return Redirect(Request.UrlReferrer.ToString());
    }

    [HttpPost]
    [MultipleButton(Name = "action", Argument = "CustomerContracts")]
    public ActionResult AdminCustomerContracts(CompanyContracts model)
    {
    return Redirect(Request.UrlReferrer.ToString());
    }

AdminCustomerContractsEdit.cshtml

<button id="buttonContractsSave" type="submit" value="ContractsSave" name="action:CustomerContracts">Save</button>

AdminCustomerNotesEdit.cshtml

<button id="buttonNotesSave" type="submit" value="NotesSave" name="action:CustomerNotes">Save</button>