Guest can't detect USB

Hi all,

host Ubuntu 12.04 64bit
guest Win7
Oracle VirtualBox
Epson Perfection 3490 photo scanner

I have encountered the problem making Win7 to detect the scanner and tried several days without a solution. I found;
VirtualBox doesn't recognize USB [duplicate]
http://askubuntu.com/questions/14008...-recognize-usb

According to #22
I have installed gnome-system-tools on the host

$ groups satimisPlease help. Thanks in advance.

Regards
satimis