Ajax.* helpers in ASP.NET MVC 3 use unobtrusive jquery so make sure that you have referenced the jquery.unobtrusive-ajax.js script in your view. Also you could use FireBug to see what’s happening under the scenes and why the form doesn’t send an AJAX request.
Also the UpdateTargetId = "form" seems suspicious especially when your form has the refresh id: @id = "refresh". Is there some other element inside your DOM with id="form"? Maybe you meant UpdateTargetId = "refresh"?