USB not found in Windows 7

I created a virtual machine using VMware vCenter and I installed Windows 7 Pro. SP1 32-Bit.

I I connect a USB key, the VHost check the key correctly:

"March 17 10:44:03.496: vmx | USB: Found device [name: Rainbow \ USB \ UltraPro vid: 04b9 pid: 0300 path: 4/1 speed: low family: vendor]"

But the OS don't check the key; I also verified the compatibility of the driver with recommended VMware's driver.

Can someone please direct me in the right direction.

Thanks in advance for any advice.