Ajax.ActionLink in MVC project

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Ajax

MVC

Hi,

I'm learning MVC, and as part of it I created an MVC project.
Since I needed menus and sub-menus I searched the net and found the superfish css and javascripts, and added them.
Then I wanted to add an Ajax button, so I saw many example of @Ajax.ActionLink
In my project, out of some reason it doesn't recognize the @Ajax. It offers me to use it as "System.Web.Mvc.Ajax" but then it doesn't recognize the ActionLink method.

here are my references from the _Layout.cshtml

<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/modernizr-1.7.min.js")" type="text/javascript"></script>
    <link href="@Url.Content("~/Content/superfish.css")" rel="stylesheet" type="text/css" />
    <script src="@Url.Content("~/Scripts/jquery-1.2.6.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/hoverIntent.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/superfish.js")" type="text/javascript"></script>
    
    <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.17/themes/redmond/jquery-ui.css" rel="Stylesheet" type="text/css"   />
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.18/jquery-ui.min.js"></script>
    <script src="<%= Url.Content("~/Scripts/MicrosoftAjax.debug.js") %>" type="text/javascript"></script>  
    <script src="<%= Url.Content("~/Scripts/MicrosoftMvcAjax.debug.js") %>" type="text/javascript"></script>

    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>

What am I doing wrong?