I found with InstallShield 2012 but it should be the same with 2010...
you have to create a "Major" upgrade. To do that, first you have to go to "Media/Upgrades" menu.
*Select "Upgrade Windows Installer Setup" and select the option "Completely uninstall old setup..." . *Click right on "Upgrade Windows Installer Setup" and "Add Major Upgrade Item". *Select your this item and:
- Select "Products having another Upgrade code" and specify the upgrade code of your setup(Warning: For me the option " Products sharing my Upgrade Code" didn't work...that's why I specified manualy my upgrade code!) - Select "any earlier version"
Now the major upgrade has been created and initialized. You just have to modify the 3 followings fields in "Installation Information/General information" each time you want to create a major upgrade:
- “Product code” - “Package code” - “Product version”. It’s not necessary to increase the first digit. You can increase the digit that you want
Note: if you don't modify “Package code” and “Product version” then only a minor upgrade will be realized.
What if you just change the Product Code, without using the Media>Upgrades UI to create a Major Upgrade Item?
It still forces an uninstall and reinstall (i.e. Major Upgrade). So is a Major Upgrade Item always required (e.g. if you don't have any special version range considerations)? If so, what does it add?
The Major Upgrade item reflects the Windows Installer 'Upgrade' table. It is used for customizing the major upgrade settings (e.g. if you want to upgrade a product with another upgrade code, or want to prevent upgrading from certain versions, or for certain languages). Without this item, your installation will allow downgrading ("major upgrade" when the installed product's version is higher)
