Use the AuthenticateEventArgs.Authenticated property in custom authentication schemes implemented in the Login.Authenticate event handler to indicate the success or failure of the user's login attempt.

Setting the AuthenticateEventArgs.Authenticated property to false indicates that the Web site user has not presented valid credentials and the System.Web.UI.WebControls.Login control should raise the Login.LoginError event in addition to displaying text that indicates the login attempt was not successful. The Login.LoginError event enables the page developer to have additional processes or action occur when user authentication is not successful. Setting AuthenticateEventArgs.Authenticated to true indicates that the user has presented valid credentials and the System.Web.UI.WebControls.Login control should raise the Login.LoggedIn event and redirect the user back to the current page or to the page indicated by Login.DestinationPageUrl.