Specific server name used by sub-reports in Crystal Reports that running in a web application

We use .NET application and Crystal Reports plug-in to run Crystal Reports in the .NET web application. Recently, we discovered that one of the reports we built throws SQL column missing error while running in the web application. It is unusual as all our reports are built in the same way.

At the end, we figured out that it was due to the report uses sub-reports and all sub-reports require to be saved with . as the server name in the Crystal Reports file. So that when it runs from the web application, it would then work successfully. In addition, we found this is the only solution and it will fail even when replacing the . with localhost.

This is an unusual solution that we normally do not see. So I record this here for future references.