This is an upgrade edition of PC Access. You cannot install this edition without a valid Disk 1 from PC Access version 4.00. If you do not own PC Access version 4.00 you will have to purchase the full version of this software.
The UAM was unable to validate your Disk 1 from PC Access version 4.00. Without a valid Disk 1 from version 4.00 you will not be able to install the user authorization for version 4.20. If you are certain that you have a valid Disk 1 from PC Access version 4.00, follow the instructions for an Internal Error.