OnLoggedIn Event On Login Page?

I want to redirect people according to their role in the asp.net membership provider. I have some code in 'OnLoggedIn' event on the login page. Here is what I tried so far, and nothing doesn't work:

The code below returns false on the .IsAuthenticated step, it says the user is not authenticated. On which step at the login page the user is authenticated, I thought the 'OnLoggedIn' event is the right place to do this.

if (HttpContext.Current.User != null)
{
if (HttpContext.Current.User.Identity.IsAuthenticated)
{
if (HttpContext.Current.User.Identity is FormsIdentity)
{
}
}
}

2nd thing I tried was to get all the roles for the user, but it doesn't return anything, returns empty array of strings, and I checked the database that the role is assigned to that specific user. Here is how I am trying:

string[] userRole = Roles.GetRolesForUser(LoginUser.UserName);

So, my question is how I can get the role on the login page, do I need to check that in some other event or on some other way.