Serial number in ABCPY.ini for MSI Package?

I have The package containing AcroPro.msi and in the same folder is the Abcpy.ini. When I deploy the package to a computer it installs successfully and shows that it has picked up the username and company name but not the serial number.

in the Abcpy.ini

;***************************************************************
;OEM Installation Options
;***************************************************************
[OEM Install]
ISX_SERIALNUMBER=1111-1111-1111-1111-1111-1111
USERNAME=jtillman@napier.medway.sch.uk
COMPANYNAME=NAPIER COMMUNITY PRIMARY AND NURSER
INSTALLDIR=

Is there any special switch or command I need to add in to make this work? I am deploying on an RM CC4 network. So I have an install command box in the package properties where I can add in command switches. Thanks.