Request.Form["SAMLResponse"] is null using web forms. AD FS

Question

I am trying to use the AspNetSaml nuget package (https://github.com/jitbit/AspNetSaml).

When my samlEndPoint is used with an MVC application and it works just fine I receive the Request.Form["SAMLResponse"] however when I use that in a web form the response is Null.

The MVC is just calling another Action Result method where as on the web form I just use it on page load of the aspx file.

any ideas?

static void Redir(Response samlResponse)
{
    //specify the SAML provider url here, aka "Endpoint"
    var samlEndpoint = "https://saml.xxxx.com/idp/SSO.saml2";
    AuthRequest request = new AuthRequest(
        "https://www.xxxx.com/", //put your app's "unique ID" here
        "**https://localhost:xxxxx/Home/SamlConsume**" //assertion Consumer Url - the redirect URL where the provider will send authenticated users
        );
    Response.Redirect(request.GetRedirectUrl(samlEndpoint));
}