[ubuntu] Can't see USB key in virtualbox, win7 as host and ubuntu as vitrual machine.

I searched in the forum but can only find issues of ubuntu as host and windows as guest.

However, I am on the opposite. I'm using win7 and install an ubuntu 14.04 in virtualbox 4.3.10.

I have already set USB controller and added usb filter in virtualbox settings. When enable my SanDisk 32GB usb drive for virtual machine, it disappears form win7 and should have appeared in Ubuntu. However I can't find any sign of this drive in ubuntu.

Can someone help me?