Ajax Helper is not working

Hello! friends i am trying to use Ajax helper in asp.net mvc project.

AddCountries.CsHtml Code is:

@model AjaxCall.Models.Countries

@using (Ajax.BeginForm("AddCountries","Country", new AjaxOptions {

HttpMethod = "POST",

OnBegin = "OnBeginRequest",

OnSuccess = "OnSuccessRequest",

OnComplete = "OnCompleteRequest",

OnFailure = "OnFailureRequest",

Confirm = "Do you want to Add Country ?"

}))

{

@Html.ValidationSummary(true, "", new { @class = "text-danger" })

@Html.LabelFor(model => model.CountriesName, htmlAttributes: new { @class = "control-label col-md-2" })

@Html.EditorFor(model => model.CountriesName, new { htmlAttributes = new { @class = "form-control" } })

@Html.ValidationMessageFor(model => model.CountriesName, "", new { @class = "text-danger" })

}

@Html.ActionLink("Back to List", "Index")

and code of AddCountries action is

[HttpPost]

public ActionResult AddCountries(Countries objCountries)

{

if (Request.IsAjaxRequest())

{

using (DbconnectionContext obj = new DbconnectionContext())

{

obj.Countries.Add(objCountries);

obj.SaveChanges();

}

return View();

}

but when i am click on "Creat" Button then postback occur and ajax is not call.

So please solve this issue...

Thanks in advance....