Software Deployment

I have a VBSCRIPT CA that is simply creating a series of local groups on the pc (XP SP2), the code runs fine without error outside the MSI if i take out the session.property line and put the computer name in as a set value. However from within the MSI i am getting error 1720 where indicated with ">|" on the script below. I am executing the script directly after AppSearch on UI. Any help will be gratefully appreciated.

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dim szGroupName, szGroupDescr, szComputerName
Dim objSystem, objGrp

szGroupName = "Radmin All Access"
szGroupDescr = "Users who can use all of Radmin's functions"
szComputerName = Session.Property("COMPUTERNAME")
CreateLocalXPGroup

szGroupName = "Radmin View Screen"
szGroupDescr = "Users who can use Radmin to View the screen"
CreateLocalXPGroup

szGroupName = "Radmin Telnet"
szGroupDescr = "Users who can use Radmin to Telnet to this client"
CreateLocalXPGroup

szGroupName = "Radmin Full Screen Control"
szGroupDescr = "Users who can use Radmin to fully remote control the screen"
CreateLocalXPGroup

szGroupName = "Radmin File Transfer"
szGroupDescr = "Users who can use Radmin to Transfer files to this client"
CreateLocalXPGroup

Sub CreateLocalXPGroup
>|Set objSystem = GetObject("WinNT://" & szComputerName)
Set objGrp = objSystem.Create("group", szGroupName)
objGrp.Description = szGroupDescr
objGrp.SetInfo
End Sub
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~