Form and Request.Form in a asp.net MVC3 Facebook Application

I'm working on a facebook app and facing a problem with my forms with MVC3 with Razor.

A. Working form:

index.cshtml

        @using (Html.BeginForm("Index", "Home", FormMethod.Post))
        {
            @Html.TextBox("tbTest", "Pouet pouet", new { Width = "500px" })
            <input type="submit" name="btnCalculate">calculer vos tarifs</input>
        } Result form : @Request.Form <br />

HomeController.cs:

public ActionResult Index()
{
    return View();
}

B. Bugging form :

About.cshtml :

        @using (Html.BeginForm("About", "Home", FormMethod.Post))
        {
            @Html.TextBox("tbTest", "Pouet pouet", new { Width = "500px" })
            <input type="submit" name="btnCalculate">calculer vos tarifs&l开发者_运维百科t;/input>
        } Result form : @Request.Form <br />

HomeController.cs :

    [CanvasAuthorize(Permissions = "user_about_me,manage_pages,offline_access")]
    public ActionResult About()
    {
        var fb = new FacebookWebClient();
        FacebookWebClient fbApi = new FacebookWebClient(FacebookWebContext.Current.AccessToken);

        dynamic result = fb.Get("me");
        return View();
    }

In apps.facebook.com/appname/home/index, the form is working, Request.Form return tbTest = Pouet pouet. In apps.facebook.com/appname/home/about, the form return nothing else but Signed_Request.

EDIT If I edit HomeController.cs like this

    [CanvasAuthorize(Permissions = "user_about_me,manage_pages,offline_access")]
    public ActionResult Index()
    {

the first page, index.cshtml, does not work anymore... The post only return Signed_Request.

So, I think I have a problem using Facebook SDK and Signed request, no ? Could you help me please. Why does the form is not sent or lost in the About page ?

for post backs you need to maintain the signed request manually.

http://facebook.stackoverflow.com/a/5364815/157260

Because you have

@using (Html.BeginForm("Index", "Home", FormMethod.Post)) 

in your About form, which causes it to POST to Index instead of About. Change it to

@using (Html.BeginForm("About", "Home", FormMethod.Post))