Subreport not displaying data

My Crystal Report is generated in Visual Studio 2008. I've linked the subreport parameters and everything runs fine when I run it from the report previewer within visual studio.

But when I deploy the report to the production server, the sub-reports don't have any data at all, even though the main data runs fine. What might be causing the subreports to stop working on the production server?

1. Did you check DataSources for main report and sub report?
2. Did you check if sub report is embedded in the main report?
3. Did you deploy the Sub report if it is not embedded?
4. How many and what kind of parameters do you use Dates, Strings, Integers ...
5. What is the error do you get? This should give you some directions where to look for a problem.
6. Can you try some other sub reports instead of the failing one.

And finally, use the old computer trick. Remove the sub report and then create/embed it again.