"Microsoft JScript runtime error: 'Sys' is undefined" on Jquery dialog that renders "Log on partialview"

Hi, I am new in jquery, ajax and mvc.

i used Jquery dialog to show a log on partial view. when it is loaded and i click in its textbox or any other place on it, i get this error:

"Microsoft JScript runtime error: 'Sys' is undefined"  

and show this script dynamic code for it: "

function onclick(event) { Sys.Mvc.AsyncForm.handleClick(this, new Sys.UI.DomEvent(event)); }

I can't use these scripts for validate textboxes, because i have jquery accordion in my page and when I use these scripts, accordion doesn't work. Also above error shows again.

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

What should i do to solve it?
How can i validate username and pass textboxes on dialog?
and ..
Can I use @Html.ActionLink in @Ajax.beginform(){}?