在Virtualbox (Linux主机)中无法识别USB设备

I tried to use USB devices without any success. It seems they are not detected by Virtualbox itself, since if I select the guest from the Virtualbox home (I'm using a Windows XP 3 guest), choose Settings -> USB -> Add filter from device, no devices is listed, even if an USB pen is attached and recognized by my Lubuntu 13.10. If i run the guest, nothing happens if I attach the device and, as above, no USB device is detected in Devices -> USB devicesI tried to use USB devices without any success.