If you have purchased a new copy of Acrobat, you can find the serial number on the registration card and on the first page of the Getting Started guide. Use this new number to initialize the program. Do not use the number on the bottom of the Adobe Acrobat box or the serial number displayed in the Acrobat About box, since this serial number does not include the checksum required for serial number validation. If your serial number does not work, please contact Adobe Customer Support. If you have purchased an Upgrade version of Acrobat, please use the Serial Number from your previous version of Acrobat.