Users get the following error message in ArchiOffice/EngineerOffice:
An Error Occurred While Validating License Key
Error: [DBNETLIB][ConnectionOpen (Invalid Instance()).]Invalid Connection
This error is generally caused due to incorrect settings specified for the SQL Server.
You can resolve this issue by correcting the settings for the SQL Server.
1. Go to these settings by clicking the Admin Options link on the ArchiOffice Login screen.
2. Select the option 'Open an Existing Company File'.
3. The Server Name on that screen probably has an invalid or incomplete name. 
You must enter the complete name of the SQL Server Instance to be used, not the literal server name.