Can't do an Upgarde in DevStudio

[Arman]

Hi all.
Please correct me if this is not the way to do a Major Upgrade in
InstallShield DevStudio:

1. The Upgrade Code needs to be the same for all versions you want to
upgrade.
2. The Product Code needs to be unique for the latest version your
about to use to Upgrade.
3. The Product Version Number must be unique for the latest version
your about to use to upgrade.

if this is the case then how come it's not upgrading? The installation
goes ahead like this is a installation on a fresh PC (a pc that never
had the software installed on it). I expect it to prompt the user
saying you must upgrade, and I have set the flag for the prompt to
true. These are the settings I have:

Version : 1.0.0.7
Product Code : {4AE8CF57-C58E-46A5-AB4D-2FFD409C9BF0}
Upgrade Code : {D7A67C2B-3844-4CA9-BE06-5FCB525E22EE}

Version : 1.0.0.8
Product Code : {CE25B861-DF33-4F02-8DB4-8BFDC1560012}
Upgrade Code : {D7A67C2B-3844-4CA9-BE06-5FCB525E22EE}
Minimume Version :
Include Min Version: Yes
Maximum Version : 1.0.0.8
Include Max Version: Yes

For some reason this doesn't work and I cant figure out why! Could
someone pleaase tell me what is the problem?