Hello again. Yes. That is absoulutely true. Some guides say that it is cASe sEnsItiVe, but it's not (at least for now. I'm not sure about the really old InstallShield built softwares). That also applies for the /s. It can be /s, /S, -s or -S. It doesn't really matter. Hmmm.. I wish I could help you on that, but I'm not really familiar with that switch. Most of my softwares record the serial in the setup.iss. But if I'm not mistaken, the /m1 switch is for SMS. I don't know the software that you're trying to install, and I can't test it becuase I don't have it. Anyways, there is a BIG difference between a serial number and a password. Are you sure that your software is asking for a serial number and not a password? There are some developers that use passwords instead of serial numbers. The password is only used in the setup, and not used by the program. It's is similar to the passwords of some SFX installers (I'm sure you're familiar with those). If you're software is asking for a password, it will not be recorded to your setup.iss. I'm not sure if this will help, but it won't hurt if you'll try using this command: start /w setup.exe /p"xxxxxxxx" /s There are cases when /s doesn't work alone. You have to use /f1 start /w setup.exe /p"xxxxxxxx" /s /f1"path_of_your_setup.iss"