Why does New <Type> With {} work but New With {} doesn't?

Question

I've always used New With {} with no issues. Why is this different?

Razor VB.NET code

Using Ajax.BeginForm(New AjaxOptions With {.HttpMethod = "Post"})
    @* no problem *@
End Using

Using Ajax.BeginForm(New With {.HttpMethod = "Post"})
    @* Value of type '<anonymous type>' cannot be converted to 'System.Web.Mvc.Ajax.AjaxOptions'. *@
End Using

Answer 1

An anonymous type (New With {}) does not extend/inherit AjaxOptions - and an object conforming to AjaxOptions is required by BeginForm.