I'm trying to create silent install of Microangelo 5.5

I followed the procedure explained here: http://unattended.msfn.org/xp/applications/installshield.htm
and created setup.iss and used the following switch: Setup.exe -s
Everything works, except it always asks me if I want to check for newer version off the internet and I need a completely silent install. Does anyone know a solution ?
TIA