detecting USB 2.0 drive

[mirandacascade]

VirtualBox release: 3.1.4
Host: MacBook Pro running Mac OS X
Guest: Windows 7 Home
Miscellaneous: Guest Additions has been installed

Step 1: start VirtualBox
Step 2: start the VM for Windows 7 Home
Step 3: insert USB thumb drive into USB port
Step 4: wait a couple minutes
Step 5: check Windows Explorer ... no evidence that the Windows 7 VM has detected the thumb drive

Additional information
- when same thumb drive inserted into USB port of a desktop running Windows 7, the desktop o/s detects drive after a few seconds
- when I'm running the MacBook Pro using the Mac OS X operating system, I can start iTunes on MacBook, insert iPod into USB port...after a few seconds, the iTunes software tells me that it has detected the iPod (in other words, I think the USB port on the MacBook Pro is functioning)

This site:

http://www.virtualbox.org/wiki/VirtualBox

indicates, "A number of extra features are available with the full VirtualBox release only ... Virtual USB Controllers. VirtualBox implements a virtual USB controller and allows you to connect arbitrary USB devices to your virtual machines without having to install device specific drivers on the host. "

I believe that I have what VirtualBox refers to as the "full VirtualBox package...for personal use and evaluation " I obtained VirtualBox by downloading it from the VirtualBox website, and I did not pay for it.

Questions:
1) assuming the information above is correct, should the Windows 7 VM have detected the USB thumb drive?
2) what steps should I be taking to troubleshoot this?

Thank you.