Unobtrusive validation doesn't work with Ajax.BeginForm

Question

I have View with Model1 where I put Ajax.BeginForm() and in this View i have PartialView with Model2 where i put Ajax.BeginForm(). So only in first form working unobtrusive validation. Why only in first form working validation?

first View

@model Model1

@using (Ajax.BeginForm("Action1","Controller",null,new AjaxOption(){ onSuccess = "alert('=)')"},null)
{

   <intput type="submit" value="Save" />
}


Model2 model2 = new Model2();
@Html.EditorFor(m=>model2)

**In Model2 view i have. **

@model Model2 
@using (Ajax.BeginForm("AddStreet","Controller",new AjaxOption(){onSuccess = "alert('=)'")},option,null)
{

        @Html.LabelFor(m => Model.Name):
        @Html.TextBoxFor(m => Model.Name)
        @Html.ValidationMessageFor(m => Model.Name)

       <intput type="submit" value="Save" />
}

Thanks @Darin Dimitrov for answer.