User.Identity.Name.ToString

[alex.NET]

Hello to everybody, i have a problem with Form authentication, when i try to get name of user logged in code below

Dim NameUsr As String = User.Identity.Name.ToString
            Dim Roles As String = GetRoles(NameUsr)
            Dim ArrRoles() As String = Split(Ruoli, ",")
            Dim Roles As New System.Security.Principal.GenericIdentity(NameUsr)
            Context.User = New System.Security.Principal.GenericPrincipal(Ruolo, ArrRoles)

the name of NameUsr is name of page instead of user.
Anybody know why ?
thanks !!