MVC :: Login Page In App Hosted On IIS 7 Integrated Mode - Its Never Getting Redirected To The Home Screen Or Invalid Login Screen

I have created my first MVC application. I am using forms authenticataion. I have created a custom action filter MyAppAuthorizationFilter which inherits from AuthorizeFilter. Inside this filter I'm authenticating the user credentials by checking them against a database table (by overriding OnAuthorize method). If the user is not authenticated, I am redirecting the users to a login page (which is view of LoginController). I am using this filter agaginst my main controller so that all actions in this filter will execute only if the user is authenticated.

I do not have any problem when I use the asp.net development server (shipped with Visual Studio). But when I deploy the app to our IIS7 server, I can see the login screen when I access the default url, but after entering the credentials (both correct and incorrect) and posting back the Login page, it stays on the Login page (clears the pwd, but not the username). Its never getting redirected to the home screen or invalid login screen.

IIS 7 server has .net framework 3.5SP1, but no MVC. So I deployed the System.Web.Mvc dll in the bin folder.

Here's my Code (I've omitted the views and models as they are not needed here):

[MyAppAuthorizationFilter]
public class MainController : Controller
{
//
// GET: / [code]......