I try to get Bios SerialNumber with thi code:

local loWMI, loItems, loItem, loLocator
CLEAR  
loLocator		= CREATEOBJECT('WBEMScripting.SWBEMLocator')
loWMIService	= loLocator.ConnectServer()
loItems			= loWMIService.ExecQuery("Select * from Win32_BIOS where PrimaryBIOS = TRUE")

For Each loItem in loItems
    ? "Caption: " , loItem.Caption
    ? "CurrentLanguage: " , loItem.CurrentLanguage
    ? "Description: " , loItem.Description
    ? "Manufacturer: " , loItem.Manufacturer
    ? "Name: " , loItem.Name
    ? "ReleaseDate: " , loItem.ReleaseDate
    ? "SerialNumber: " , loItem.SerialNumber
    ? "SMBIOSBIOSVersion: " , loItem.SMBIOSBIOSVersion
    ? "SMBIOSMajorVersion: " , loItem.SMBIOSMajorVersion
    ? "SMBIOSMinorVersion: " , loItem.SMBIOSMinorVersion
    ? "SMBIOSPresent: " , loItem.SMBIOSPresent
    ? "Status: " , loItem.Status
    ? "Version: " , loItem.Version
Next

and I received something like this:

Caption: Award Modular BIOS v6.00PG
CurrentLanguage: n|US|iso8859-1
Description: Award Modular BIOS v6.00PG
Manufacturer: Award Software International, Inc.
Name: Award Modular BIOS v6.00PG
ReleaseDate: 20030912******.******+***
SerialNumber:
SMBIOSBIOSVersion: F8
SMBIOSMajorVersion: 2
SMBIOSMinorVersion: 3
SMBIOSPresent: .T.
Status: OK
Version: GBT - 42302e31
Why I don't get SerialNumber and I have "******.******+***" after the Release date?
Can someone help me?