I'm on a Mac running OS X 10.5.8 using Extension Manager 5.0.334. When Extension Manager launches, it only recognizes four of the installed Creative Suite applications: Fireworks, Dreamweaver, InCopy and Bridge. Installed CS5 apps also include InDesign, Photoshop, Illustrator, Flash, Flash Catalyst, etc. None of those show up in the Extension Manager.
When I attempt to install an extension for one of those apps (namely InDesign,) I either get an error message saying "Failed to install the Creative Suite Extension "Macintosh HD: Users: username:Desktop: Overlay Creator.zxp. Please make sure the manifest.xml of this extension is valid and the Extension Manager recognizes at least one product which the extension supports. The extension will not be installed" OR "This extension can not be installed, it requires InDesign version 7.0 or greater." (I have InDesign v7.03 installed)
I've reinstalled the Creative Suite, reinstalled the Extension Manager and reinstalled my operating system and none of those has had any effect on the programs that the Extension Manager recognizes.