If you are getting the error while running the crystal report like this. "This field name is not known". The below step should fix your problem.
Ensure that database view is updated corrected and correct field name is being reffered from Crystal Report.
Then open the crystal report in Crystal Report view and From the Database Menu, select option " Verify Database " .
It would ask you credentials and then would ask whether you want to update. Click Okay and Save the report file.
Now try to run the report again. You should see the report without any problem. This was the solution I saw recently somewhere, and thought of posting it for everyone else. Hope this helps someone.
