SW2008 1.1 service pack install problem with 16 digit serial number

I have installed a new network version of SW2008 and wantedto update the software with the latest service pack (1.1). Theservice pack installer prompts me for a 20 digit serial number butwe have a 16 digit serial number because we are using a networklicense. How do I install this service pack?
SolidworksAdministration