For Creative Suite 5.5 suites and individual products:
If you purchased the correct upgrade, install the upgrade as a trial version(If you need help with the installation process, see Install Adobe Creative Suite 5.5.) and then contact Adobe for assistance before the trial expires.
Enter a suite- or product-specific serial number. For example, a Photoshop serial number doesn't work when you install Illustrator.
You cannot solve this problem on your own. Have both your upgrade and previous version serial numbers(if applicable) handy, be at your computer and ready to start the install process and contact Adobe. Click the Chat now button below to initiate a chat with Adobe Support.