system resource USB serial-number SET new one for Spiceworks

we realise that Spiceworks gets as a serial number our 750GL the serial-number of the USB controller that doesn’t even there.
so i am trying to rename the serial-number to another NUMBER or NAME

[admin@RB750] /system resource usb> print detail
0 device=“1:1” vendor=“Linux 3.3.5 ehci_hcd” name=“RB400 EHCI”
serial-number=“rb400_usb” vendor-id=“0x1d6b” device-id=“0x0002”
speed=“480 Mbps” ports=1 usb-version=“2.00”

**[admin@RB750] /system resource usb> set serial-number=**NEWNUMBER
he ask for a number
numbers:
ask for a help with a “?” and then shows
Numbers ::= see documentation

it tryed “0” , “1” “1:1” someone can give me an advice ?
thanks