Driver Modem Agere Nfa-01a When I Install Agere Usb Soft Modem's Driver Why It Says UNKNOWN DEVICE?

When i install agere usb soft modem's driver why it says UNKNOWN DEVICE? - driver modem agere nfa-01a

I bought a laptop ASUS k40ab and has no dial-up modem. I bought the USB modem and Agere even if I have the driver and the USB modem for laptops, which says to install unknown device. Os Laptop Vista 32-bit. Why not a modem?