The Franklin Access manager application woks with the U210 USB modem. This means it won't detect any other device that isn't compatible or made to be compatible by the developers.
However, if you refer to the USB Modem as Aircard, then the drivers might not be installed. Go to Start > Run > Device Manager and check the list. The device should be listed with a yellow sign. You need to install the drivers by plugging the modem and accessing the drive in Computer. You'll find a setup package that needs to be installed. After this procedure, the software will detect the device.