Ajax.BeginForm does not raise "submit" event in IE 7 / 8

In ASP.NET MVC 3, I've declared an ajax form like this:

@using (Ajax.BeginForm("SaveRegistrationConfirmationRequest", null, new AjaxOptions { UpdateTargetId = "verify-email-result", HttpMethod = "Post" }, new { id = "request-form" }))

and I'm using jQuery to bind to the "submit" event (the alert is just fo开发者_开发问答r testing):

$("#request-form").submit(function () {
    alert("submit");
    if (!$("#agree-checkbox").is(":checked")) {
        $("#agree-dialog").dialog("open");
        return false;
    }
});

In Chrome and Firefox on Windows, the event handler is called and I see the alert. In IE 7 and 8, I don't see the alert and the form is submitted.

If I change the code to use a non-ajax form, then the handler is called in IE:

@using (Html.BeginForm("SaveRegistrationConfirmationRequest", "Account", FormMethod.Post, new { id = "request-form" }))

What do I need to do to get this working with an ajax form in IE? Any help would be appreciated!

---

I ended up using the ajaxSend event:

$("#request-form").ajaxSend(function (evt, request, settings) {
    if (!$("#agree-checkbox").is(":checked")) {
        request.abort();
        $("#agree-validation").addClass("field-validation-error");
        $("#agree-validation").removeClass("field-validation-valid");

    }
});

This works in IE 7 and 8, Firefox, and Chrome.