I have found that if I put this code at the top of my class, that is works:

    Private Declare Unicode _
            Function GetPrivateProfileString _
            Lib "kernel32" _
            Alias "GetPrivateProfileStringW" _
            (ByVal lpApplicationName As String, _
             ByVal lpKeyName As String, _
             ByVal lpDefault As String, _
             ByVal lpReturnedString As String, _
             ByVal nSize As Int32, _
             ByVal lpFileName As String) As Int32

What I don't understand is that I never had that code before and all was working ok.