OnLoggedIn Event on ASP.NET Login Page

I want to redirect people according to their role in asp.net membership provider. I have code in the OnLoggedIn event on the login page. Here is what I have tried so far and nothing works:

The code below returns false in the step .IsAuthenticated, it says that the user is not authenticated. At what stage on the login page the user is authenticated, I thought that the OnLoggedIn event is the right place for this.

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

The second thing I tried is to get all the roles for the user, but returns nothing, returns an empty array of strings, and I checked the database that the role was assigned to this specific user. This is how I try:

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

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