If you do a Google search on this error code, it means "Invalid identifier" or "Invalid Column Name". If your were actually unable to connect to the database, you would get a different error.
Are you using a command in your report? If so, I would try to run the SQL in a tool outside of Crystal - I generally use Toad, but there are tools that come with Oracle as well - and make sure it runs correctly there. If you're not using a command, go to the Database menu and click on Show SQL Query then copy the query from there and try to run it outside of Crystal to diagnose the problem.
-Dell