InstallShield 2010 - 1603 Fatal Error [Windows Installer] (Windows 7 Only)

I created an MSI InstalScript Project where i deploy a web based (ASP.NET) precompiled project copying the files during installation in the \inetpub\wwwroot\projectnamefolder, creating an AppPool and the virtual开发者_开发技巧 dir of course in the IIS. The setup works great in windows XP Pro (SP3 i used). But soon as i try in Windows 7 (tried Ultimate and Home Premium) i get a -1603 Fatal Error during installation...Windows Installer Help (MSI.chm) or MSDN for more info....

Dying to fix this...

[Edit] I think error occurs when trying to create the Application in the IIS.

[FIXED] Enable 32 Bit Apllications needs to be true when creating Application Pools through InstallShield in a 64 bit OS!

No permission. See this MS support article So you have write access to the directory but does the account have permissions to modify the IIS settings?